2024, 38(4): 379-383.
doi: 10.3969/j.issn.1007-2993.2024.04.001
Abstract:
Combined with the actual situation of engineering investigation, the characteristics of core pipe drilling, threaded drilling, three-wing drilling and impact drilling, such as adapted strata, the drilling process, disturbance and destruction to soil, operation procedure, were analyzed. The advantages and disadvantages of these four kinds of drilling techniques were summarized in detail. According to engineering investigation experience and the analysis and research on the mechanism of each drilling process, threaded drilling has absolute advantages in terms of the accuracy of stratification discrimination, the quality of samples and the reliability of standard penetration test data for clay and interlayered or mixed soil dominated by clay. There is no major breakthrough in four kinds of drilling technology widely used in the field of engineering investigation, and all kinds of related drilling equipment are aging. This analysis further described the progress of improvement and optimization on drilling technology, and the research direction and expectation of drilling technology in engineering survey were put forward.
Combined with the actual situation of engineering investigation, the characteristics of core pipe drilling, threaded drilling, three-wing drilling and impact drilling, such as adapted strata, the drilling process, disturbance and destruction to soil, operation procedure, were analyzed. The advantages and disadvantages of these four kinds of drilling techniques were summarized in detail. According to engineering investigation experience and the analysis and research on the mechanism of each drilling process, threaded drilling has absolute advantages in terms of the accuracy of stratification discrimination, the quality of samples and the reliability of standard penetration test data for clay and interlayered or mixed soil dominated by clay. There is no major breakthrough in four kinds of drilling technology widely used in the field of engineering investigation, and all kinds of related drilling equipment are aging. This analysis further described the progress of improvement and optimization on drilling technology, and the research direction and expectation of drilling technology in engineering survey were put forward.
2024, 38(4): 384-390.
doi: 10.3969/j.issn.1007-2993.2024.04.002
Abstract:
A project in Beijing CBD has a foundation pit depth of 36 meters. Due to space limitations, a “two walls integration”+internal support system was adopted to achieve the functions of retaining soil and water in the foundation pit, while completing the construction of the exterior wall of the underground structure. To improve the quality and construction efficiency of the project, technological innovations have been made in the connection between the ground connecting wall and the main structure, the treatment method of groove section joints, and the combination of limited space guide walls and pre-bracing of adjacent buildings. Good engineering results have been achieved, which can be used as a reference for similar projects.
A project in Beijing CBD has a foundation pit depth of 36 meters. Due to space limitations, a “two walls integration”+internal support system was adopted to achieve the functions of retaining soil and water in the foundation pit, while completing the construction of the exterior wall of the underground structure. To improve the quality and construction efficiency of the project, technological innovations have been made in the connection between the ground connecting wall and the main structure, the treatment method of groove section joints, and the combination of limited space guide walls and pre-bracing of adjacent buildings. Good engineering results have been achieved, which can be used as a reference for similar projects.
2024, 38(4): 391-397.
doi: 10.3969/j.issn.1007-2993.2024.04.003
Abstract:
During close-spaced tunnel construction passing through existing bridge piles, and based on the field measured data, the change rules of bridge pile settlement, the settlement proportion of each stage, the distribution of soft strata in the tunnel body, and the impact of sleeve valve pipe driving method on the bridge pile settlement were analyzed. The conclusion shows that when shield tunneling side through bridge piles in soft strata, the vertical displacement of the bridge pile shows the change rule of “first rising slightly, then sinking”; the settlement of bridge piles mainly occurs during and one week after the shield passes, accounting for 80%～90% of the total settlement; when the plane clear distance between the tunnel and the bridge pile is less than 2D, the bridge pile adjacent to the tunnel shall be pre-grouted with sleeve valve pipe around the pile for reinforcement, which can effectively reduce the impact of shield construction on the settlement of the bridge pile; the higher the distribution proportion of soft soil layer in the tunnel body, the greater the settlement of bridge piles; the sleeve valve pipe grouting hole around the pile shall be set vertically to avoid the blind area of grouting, so as to ensure the effect of soil reinforcement and bridge pile settlement control.
During close-spaced tunnel construction passing through existing bridge piles, and based on the field measured data, the change rules of bridge pile settlement, the settlement proportion of each stage, the distribution of soft strata in the tunnel body, and the impact of sleeve valve pipe driving method on the bridge pile settlement were analyzed. The conclusion shows that when shield tunneling side through bridge piles in soft strata, the vertical displacement of the bridge pile shows the change rule of “first rising slightly, then sinking”; the settlement of bridge piles mainly occurs during and one week after the shield passes, accounting for 80%～90% of the total settlement; when the plane clear distance between the tunnel and the bridge pile is less than 2D, the bridge pile adjacent to the tunnel shall be pre-grouted with sleeve valve pipe around the pile for reinforcement, which can effectively reduce the impact of shield construction on the settlement of the bridge pile; the higher the distribution proportion of soft soil layer in the tunnel body, the greater the settlement of bridge piles; the sleeve valve pipe grouting hole around the pile shall be set vertically to avoid the blind area of grouting, so as to ensure the effect of soil reinforcement and bridge pile settlement control.
2024, 38(4): 398-401.
doi: 10.3969/j.issn.1007-2993.2024.04.004
Abstract:
The application of Kalman filtering in denoising static leveling and fixed inclinometer raw data was investigated. The results indicated that under slow deformation conditions, Kalman filtering can effectively filter out noise in the original data, provide reliable results, and reveal the true deformation situation of the monitored object. But in case of sudden deformation, Kalman filtering reflects lag. Therefore, in practical applications, the data before and after filtering should be comprehensively used to more accurately analyze deformation trends and patterns. It provided new ideas and methods for noise processing in automatic monitoring data. The application of Kalman filtering can further improve the accuracy and reliability of monitoring data, providing support for engineering safety monitoring and geological disaster warning.
The application of Kalman filtering in denoising static leveling and fixed inclinometer raw data was investigated. The results indicated that under slow deformation conditions, Kalman filtering can effectively filter out noise in the original data, provide reliable results, and reveal the true deformation situation of the monitored object. But in case of sudden deformation, Kalman filtering reflects lag. Therefore, in practical applications, the data before and after filtering should be comprehensively used to more accurately analyze deformation trends and patterns. It provided new ideas and methods for noise processing in automatic monitoring data. The application of Kalman filtering can further improve the accuracy and reliability of monitoring data, providing support for engineering safety monitoring and geological disaster warning.
2024, 38(4): 402-407.
doi: 10.3969/j.issn.1007-2993.2024.04.005
Abstract:
River crossing construction of shield tunneling causes loss of soil mass and settlement of surface and upper bridges. Based on a shield construction project with river crossing construction in a muddy soft soil area, the ground and bridge pier settlement characteristics caused by river crossing construction under shallow overburden conditions were measured and analyzed. A method for predicting the settlement caused by the river crossing construction of shield tunneling considering construction sequences and process parameters was proposed using the long-short-term memory network model. The settlement control measures of construction were also discussed. The research shows that the settlement change of monitoring points in front of the river caused by river crossing construction can be divided into four stages. The surface settlement of the measuring points near the river is greater than that of other measuring points of the shield section. The settlement of pile foundations mainly occurs during the process of shield tunneling crossing the river. The analysis based on the measured data shows that the long-short-term memory network model can better characterize the construction impact parameters and corresponding settlement of each ring and can be used for the settlement prediction analysis caused by the river crossing construction of shield tunneling.
River crossing construction of shield tunneling causes loss of soil mass and settlement of surface and upper bridges. Based on a shield construction project with river crossing construction in a muddy soft soil area, the ground and bridge pier settlement characteristics caused by river crossing construction under shallow overburden conditions were measured and analyzed. A method for predicting the settlement caused by the river crossing construction of shield tunneling considering construction sequences and process parameters was proposed using the long-short-term memory network model. The settlement control measures of construction were also discussed. The research shows that the settlement change of monitoring points in front of the river caused by river crossing construction can be divided into four stages. The surface settlement of the measuring points near the river is greater than that of other measuring points of the shield section. The settlement of pile foundations mainly occurs during the process of shield tunneling crossing the river. The analysis based on the measured data shows that the long-short-term memory network model can better characterize the construction impact parameters and corresponding settlement of each ring and can be used for the settlement prediction analysis caused by the river crossing construction of shield tunneling.
2024, 38(4): 408-414.
doi: 10.3969/j.issn.1007-2993.2024.04.006
Abstract:
The large-angle cable-stayed pile support structure can save space outside the pit, has advantages such as convenient construction and low cost, and is suitable for scenarios where the anchoring space outside the pit is limited. To further study its deformation and stress mechanism, typical medium-dense sandy soil was selected for numerical modeling of a single soil layer, and the stress and deformation characteristics of the structure were analyzed by changing the angle of the anchor cable and the excavation depth. The results show that the change of the angle of the anchor cable has a great impact on the stress and deformation of the structure, and simplifying the anchor cable into a horizontal elastic support will produce a large calculation deviation. It is necessary to consider the effect of axial force on the flexural and shear bearing capacity of pile and the vertical bearing capacity of single pile. On this basis, the constraint effect of anchor cable on soil retaining pile is considered as inclined elastic support, and a mechanical calculation model which is more in line with the actual stress state and the plane rod system finite element method were established. It is applied to a practical project and compared with the monitoring data. The results show that: large angle cable-stayed pile has good supporting performance, and the mechanical calculation model proposed can reflect the stress and deformation characteristics of this new structure.
The large-angle cable-stayed pile support structure can save space outside the pit, has advantages such as convenient construction and low cost, and is suitable for scenarios where the anchoring space outside the pit is limited. To further study its deformation and stress mechanism, typical medium-dense sandy soil was selected for numerical modeling of a single soil layer, and the stress and deformation characteristics of the structure were analyzed by changing the angle of the anchor cable and the excavation depth. The results show that the change of the angle of the anchor cable has a great impact on the stress and deformation of the structure, and simplifying the anchor cable into a horizontal elastic support will produce a large calculation deviation. It is necessary to consider the effect of axial force on the flexural and shear bearing capacity of pile and the vertical bearing capacity of single pile. On this basis, the constraint effect of anchor cable on soil retaining pile is considered as inclined elastic support, and a mechanical calculation model which is more in line with the actual stress state and the plane rod system finite element method were established. It is applied to a practical project and compared with the monitoring data. The results show that: large angle cable-stayed pile has good supporting performance, and the mechanical calculation model proposed can reflect the stress and deformation characteristics of this new structure.
2024, 38(4): 415-419.
doi: 10.3969/j.issn.1007-2993.2024.04.007
Abstract:
A riverbank foundation pit utilized a triaxial cement-soil mixed wall for water seepage prevention. During excavation, water gushing, sand effusion, and seepage destruction occurred. After several unsuccessful attempts at sealing and remediation, a combined technique of dual-liquid grouting with jet grouting piles was proposed. The issues of water and sand gushing were solved, and the remediation and reinforcement of the seepage control were accomplished, without adversely affecting the pit or its surrounding environment, thereby ensuring the continuation of subsequent excavation works. Taking this project as a case study, the process of remediation and reinforcement undertaken for the seepage damage of this foundation pit is outlined, and the technical key points of the dual-liquid jet grouting piles technique are summarized.
A riverbank foundation pit utilized a triaxial cement-soil mixed wall for water seepage prevention. During excavation, water gushing, sand effusion, and seepage destruction occurred. After several unsuccessful attempts at sealing and remediation, a combined technique of dual-liquid grouting with jet grouting piles was proposed. The issues of water and sand gushing were solved, and the remediation and reinforcement of the seepage control were accomplished, without adversely affecting the pit or its surrounding environment, thereby ensuring the continuation of subsequent excavation works. Taking this project as a case study, the process of remediation and reinforcement undertaken for the seepage damage of this foundation pit is outlined, and the technical key points of the dual-liquid jet grouting piles technique are summarized.
2024, 38(4): 420-426.
doi: 10.3969/j.issn.1007-2993.2024.04.008
Abstract:
During the construction period, it is necessary to ensure that the existing railway transportation line that originally passed through here was not affected. The project of Fengtai station reconstruction was divided into three phases of construction, and construction was carried out in two phases in sequence and post-cast strips were set up at the junction of the phased construction. Due to the station's main structure consisting mainly of cast-in-place concrete frame structures, the presence of post-cast strips has a significant impact on the progress of subsequent construction. Based on the deformation calculation analysis of the superstructure-foundation-soil, a refined modeling of the strata, structure, and construction steps was carried out. The results show that the differential settlement caused by the later construction on both sides of the settlement post pouring belt meets the specifications and design requirements. The settlement post-cast strips were cancelled and created conditions to ensure the construction period. Verified by settlement measurement data, the numerical calculation prediction results are reliable, and this method can be used as a reference for similar projects.
During the construction period, it is necessary to ensure that the existing railway transportation line that originally passed through here was not affected. The project of Fengtai station reconstruction was divided into three phases of construction, and construction was carried out in two phases in sequence and post-cast strips were set up at the junction of the phased construction. Due to the station's main structure consisting mainly of cast-in-place concrete frame structures, the presence of post-cast strips has a significant impact on the progress of subsequent construction. Based on the deformation calculation analysis of the superstructure-foundation-soil, a refined modeling of the strata, structure, and construction steps was carried out. The results show that the differential settlement caused by the later construction on both sides of the settlement post pouring belt meets the specifications and design requirements. The settlement post-cast strips were cancelled and created conditions to ensure the construction period. Verified by settlement measurement data, the numerical calculation prediction results are reliable, and this method can be used as a reference for similar projects.
2024, 38(4): 427-430.
doi: 10.3969/j.issn.1007-2993.2024.04.009
Abstract:
A Class II residential land project in Daxing District, Beijing is surrounded by multiple high-rise residential buildings and an underground parking garage. To eliminate the adverse effects of differential settlement, multiple post-cast strips were installed. The existence of post-cast strips seriously restricts the project schedule. Therefore, based on the geological conditions of the site, the foundation scheme, and the distribution of loads on the upper structure, PLAXIS3D was used for settlement analysis, and the early closure of settlement post-cast strips was feasibility according to practical engineering experience. The project implemented an early closure of the post-cast strips, thereby accomplishing the intended objectives.
A Class II residential land project in Daxing District, Beijing is surrounded by multiple high-rise residential buildings and an underground parking garage. To eliminate the adverse effects of differential settlement, multiple post-cast strips were installed. The existence of post-cast strips seriously restricts the project schedule. Therefore, based on the geological conditions of the site, the foundation scheme, and the distribution of loads on the upper structure, PLAXIS3D was used for settlement analysis, and the early closure of settlement post-cast strips was feasibility according to practical engineering experience. The project implemented an early closure of the post-cast strips, thereby accomplishing the intended objectives.
2024, 38(4): 431-435.
doi: 10.3969/j.issn.1007-2993.2024.04.010
Abstract:
Combined with a foundation pit project in Kunming, numerical modeling was established using finite element software MIDAS GTS. Three numerical simulations were carried out on the surface settlement of the foundation pit and deformation of the neighboring buildings, including no buildings in the surrounding, the longitudinal wall of the building parallelling to the foundation pit, and the longitudinal wall of the building being perpendicular to the foundation pit. The results show that: (1) the settlement of the floor plate of the neighboring building near the pit is larger, the building as a whole is tilted to the pit, and the two ends of the floor plate in the width direction are synchronously sinking and symmetrically concave, compared to the settlement of the building when the longitudinal wall is perpendicular to the pit, and (2) in the case of the no building or building with longitudinal wall parallel to the pit, the maximum settlement of the surface of the pit occurs in the range of 5~7.5 m from the edge of the pit, which is approximately (0.5~0.75)H (H is the depth of the pit); for the case where the longitudinal wall of the building is perpendicular to the pit, the maximum settlement of the surface of the pit occurs at a distance of about 9~12 m from the edge of the pit, which is about (0.9~1.2)H.
Combined with a foundation pit project in Kunming, numerical modeling was established using finite element software MIDAS GTS. Three numerical simulations were carried out on the surface settlement of the foundation pit and deformation of the neighboring buildings, including no buildings in the surrounding, the longitudinal wall of the building parallelling to the foundation pit, and the longitudinal wall of the building being perpendicular to the foundation pit. The results show that: (1) the settlement of the floor plate of the neighboring building near the pit is larger, the building as a whole is tilted to the pit, and the two ends of the floor plate in the width direction are synchronously sinking and symmetrically concave, compared to the settlement of the building when the longitudinal wall is perpendicular to the pit, and (2) in the case of the no building or building with longitudinal wall parallel to the pit, the maximum settlement of the surface of the pit occurs in the range of 5~7.5 m from the edge of the pit, which is approximately (0.5~0.75)H (H is the depth of the pit); for the case where the longitudinal wall of the building is perpendicular to the pit, the maximum settlement of the surface of the pit occurs at a distance of about 9~12 m from the edge of the pit, which is about (0.9~1.2)H.
2024, 38(4): 436-439.
doi: 10.3969/j.issn.1007-2993.2024.04.011
Abstract:
The bearing capacity of post grouting piles in deep soft soil layers is influenced by multiple factors. Taking three sets of post grouting piles at the pile end of a certain project in Shanghai as the research object, the influencing factors on the bearing capacity of post grouting piles were investigated, with the ninth layer of silt layer as the bearing layer of the pile foundation. The results indicated that the bearing capacity of post grouting piles was greatly influenced by the drilling process, grouting process, and sediment thickness. To avoid the influence of the above factors, the reverse circulation drilling and circulation mud sand removal construction technology were adopted, and the structure of the grouting hole was improved. The use of alternating high and low pressure grouting significantly increased the grouting amount, effectively cemented the sediment at the bottom of the hole, and solved the problem of insufficient bearing capacity of grouting pile in the area.
The bearing capacity of post grouting piles in deep soft soil layers is influenced by multiple factors. Taking three sets of post grouting piles at the pile end of a certain project in Shanghai as the research object, the influencing factors on the bearing capacity of post grouting piles were investigated, with the ninth layer of silt layer as the bearing layer of the pile foundation. The results indicated that the bearing capacity of post grouting piles was greatly influenced by the drilling process, grouting process, and sediment thickness. To avoid the influence of the above factors, the reverse circulation drilling and circulation mud sand removal construction technology were adopted, and the structure of the grouting hole was improved. The use of alternating high and low pressure grouting significantly increased the grouting amount, effectively cemented the sediment at the bottom of the hole, and solved the problem of insufficient bearing capacity of grouting pile in the area.
2024, 38(4): 440-446.
doi: 10.3969/j.issn.1007-2993.2024.04.012
Abstract:
To study the dynamic and static responses of existing railway bridge piers under the influence of percussion drilling, the theoretical analysis, numerical simulation, and field test of the influence of percussion drilling on railway bridge piers were carried out. The theoretical analyses show that the maximum vibration velocity of the railway track under the condition of percussion drilling and the vibration velocity of the existing bridge pier under the coupling of percussion drilling construction and train vibration meet the requirements of the code. The numerical simulation results show that the total displacement, horizontal displacement, and vertical displacement of the existing pier top are all within the scope of the code. Field tests show that the displacement and vibration velocity of the affected piers meet the requirements of the code. However, data comparisons show that the theoretical analysis and numerical simulation do not consider the adverse effects of uneven foundation and construction disturbance, and the calculation results tend to be dangerous.
To study the dynamic and static responses of existing railway bridge piers under the influence of percussion drilling, the theoretical analysis, numerical simulation, and field test of the influence of percussion drilling on railway bridge piers were carried out. The theoretical analyses show that the maximum vibration velocity of the railway track under the condition of percussion drilling and the vibration velocity of the existing bridge pier under the coupling of percussion drilling construction and train vibration meet the requirements of the code. The numerical simulation results show that the total displacement, horizontal displacement, and vertical displacement of the existing pier top are all within the scope of the code. Field tests show that the displacement and vibration velocity of the affected piers meet the requirements of the code. However, data comparisons show that the theoretical analysis and numerical simulation do not consider the adverse effects of uneven foundation and construction disturbance, and the calculation results tend to be dangerous.
2024, 38(4): 447-452.
doi: 10.3969/j.issn.1007-2993.2024.04.013
Abstract:
Nujiang airport is located in the high intensity seismic mountainous area in the southwest of China.The stability of the slope under the high fill load and seismic load is the key factor restricting the airport construction. The methods of theoretical analysis and numerical simulation were used to analyze the stability of the high filling slope. The results show that under the high filling load of the retaining wall, most of the base of the retaining wall does not meet the bearing capacity requirements, and the differential settlement of the retaining wall is large. The comprehensive shear strength parameters of the filling interface should meet c≥50 kPa and φ≥25° to ensure the stability of the backfill soil. The seismic action has a great impact on the stress and deformation of backfill soil, and the deformation of retaining wall increases by 0.6～1.1 mm, which may cause the cracking of retaining wall. It is suggested to strengthen the basement rock mass and carry out seismic design for the retaining wall.
Nujiang airport is located in the high intensity seismic mountainous area in the southwest of China.The stability of the slope under the high fill load and seismic load is the key factor restricting the airport construction. The methods of theoretical analysis and numerical simulation were used to analyze the stability of the high filling slope. The results show that under the high filling load of the retaining wall, most of the base of the retaining wall does not meet the bearing capacity requirements, and the differential settlement of the retaining wall is large. The comprehensive shear strength parameters of the filling interface should meet c≥50 kPa and φ≥25° to ensure the stability of the backfill soil. The seismic action has a great impact on the stress and deformation of backfill soil, and the deformation of retaining wall increases by 0.6～1.1 mm, which may cause the cracking of retaining wall. It is suggested to strengthen the basement rock mass and carry out seismic design for the retaining wall.
2024, 38(4): 453-458.
doi: 10.3969/j.issn.1007-2993.2024.04.014
Abstract:
A deep foundation pit is situated in the flood plain of Nanjing. The geological condition is that the flowing plastic mucky silty clay is distributed in the upper part, and a deep gravel layer with high permeability and strong bearing ability is distributed in the lower part. The foundation pit is a narrow cuboid with 250 m in east-west length, 50 m in north-south width, and 11~14 m in depth. Some adjacent sensitive buildings are existed in the south side of the foundation pit while some important municipal pipelines including natural gas pipeline and water supply pipe are close to the north side of the foundation pit. Based on the scheme comparison and pile testing, the combined supporting system composed of retaining pile and concrete inner support was adopted. To effectively control the underground water level, the triaxial cement-soil mixing column was taken as the waterproof curtain and the drainage was carried out through the dewatering well inside the foundation pit. Considering the mechanical property of narrow foundation pit and deformation control of the surrounding environment, the supporting structure and waterproof curtain in the south of the foundation pit were enhanced. A specific scheme of subarea and time-sharing construction was conducted to avoid the shape effect induced by pit excavation. The rational construction parameters for ultra-long waterproof curtain crossing different stratums were determined using pile testing. The detection and monitoring results show that the waterproof curtain is continuous and integral. Both the strength and deformation of structure and surrounding environment fit the requirement of design and specification. These situations can be a reference for the similar foundation pit engineering.
A deep foundation pit is situated in the flood plain of Nanjing. The geological condition is that the flowing plastic mucky silty clay is distributed in the upper part, and a deep gravel layer with high permeability and strong bearing ability is distributed in the lower part. The foundation pit is a narrow cuboid with 250 m in east-west length, 50 m in north-south width, and 11~14 m in depth. Some adjacent sensitive buildings are existed in the south side of the foundation pit while some important municipal pipelines including natural gas pipeline and water supply pipe are close to the north side of the foundation pit. Based on the scheme comparison and pile testing, the combined supporting system composed of retaining pile and concrete inner support was adopted. To effectively control the underground water level, the triaxial cement-soil mixing column was taken as the waterproof curtain and the drainage was carried out through the dewatering well inside the foundation pit. Considering the mechanical property of narrow foundation pit and deformation control of the surrounding environment, the supporting structure and waterproof curtain in the south of the foundation pit were enhanced. A specific scheme of subarea and time-sharing construction was conducted to avoid the shape effect induced by pit excavation. The rational construction parameters for ultra-long waterproof curtain crossing different stratums were determined using pile testing. The detection and monitoring results show that the waterproof curtain is continuous and integral. Both the strength and deformation of structure and surrounding environment fit the requirement of design and specification. These situations can be a reference for the similar foundation pit engineering.
2024, 38(4): 459-464.
doi: 10.3969/j.issn.1007-2993.2024.04.015
Abstract:
The landslide disasters in the north and south mountain areas of Tianshui are extremely developed, and it is extremely challenging to build roads in this area. Taking the analysis and remediation of a large tractive deposit landslide in Quping village, Tianshui as an example, engineering geological mapping, drilling, deep displacement monitoring, and indoor mechanical tests were conducted to analyze the form, deformation, and development characteristics of the landslide. The disaster mechanism of the landslide was studied and its stability was evaluated, and remediation measures were provided. The results show that the Quping landslide could be divided into two stages in plane morphology, the sliding direction is broken line, the sliding body is mainly composed of silty clay, and the sliding bed is Neogene mudstone, which is a typical accumulation landslide. The buried depth of the sliding surface is 6.0~13.0 m, and the deformation mode is traction type, which is induced by the geological environment of the slope, earthquake, heavy rainfall, and other natural factors. In view of the landslide, a set of treatment plans such as drainage interception, retaining, and monitoring was put forward, which can provide a reference for the control of similar landslide disasters.
The landslide disasters in the north and south mountain areas of Tianshui are extremely developed, and it is extremely challenging to build roads in this area. Taking the analysis and remediation of a large tractive deposit landslide in Quping village, Tianshui as an example, engineering geological mapping, drilling, deep displacement monitoring, and indoor mechanical tests were conducted to analyze the form, deformation, and development characteristics of the landslide. The disaster mechanism of the landslide was studied and its stability was evaluated, and remediation measures were provided. The results show that the Quping landslide could be divided into two stages in plane morphology, the sliding direction is broken line, the sliding body is mainly composed of silty clay, and the sliding bed is Neogene mudstone, which is a typical accumulation landslide. The buried depth of the sliding surface is 6.0~13.0 m, and the deformation mode is traction type, which is induced by the geological environment of the slope, earthquake, heavy rainfall, and other natural factors. In view of the landslide, a set of treatment plans such as drainage interception, retaining, and monitoring was put forward, which can provide a reference for the control of similar landslide disasters.
2024, 38(4): 465-470.
doi: 10.3969/j.issn.1007-2993.2024.04.016
Abstract:
The layout of deep buried tunnels and the stability of surrounding rocks are closely related to ground stress conditions. The hydraulic fracturing method is a widely used and mature in-situ stress testing method for deep-buried tunnels. The hydraulic fracturing method was used to test the in-situ ground stress of a tunnel in East China mountainous area, and the maximum and minimum horizontal principal stress and other mechanical parameters were obtained, the characteristics of ground stress were analyzed, which can provide a scientific basis for the layout of tunnel lines and the prediction of rock burst in the surrounding rock. The research showed that the horizontal principal stress of the tunnel increases linearly with the buried depth, and two stress types of thrust stress and strike-slip stress were developed from shallow to deep, respectively. The dominant direction of the maximum horizontal principal stress in the buried depth of the tunnel is consistent with the direction of regional geological tectonic stress, and the angle between the maximum horizontal principal stress and the tunnel strike is less than the optimal angle, which has a certain impact on the stability of surrounding rock. The rock burst risk of surrounding rock increases with the increase of depth, there may be slight rock burst in the surrounding rock at the depth of the tunnel, and relevant measures should be taken to release the ground stress of surrounding rock in time to ensure the construction safety. The research results provide a certain technical reference for the survey, planning, and design of oil and gas pipelines, transportation, and other engineering construction in mountainous areas in the future.
The layout of deep buried tunnels and the stability of surrounding rocks are closely related to ground stress conditions. The hydraulic fracturing method is a widely used and mature in-situ stress testing method for deep-buried tunnels. The hydraulic fracturing method was used to test the in-situ ground stress of a tunnel in East China mountainous area, and the maximum and minimum horizontal principal stress and other mechanical parameters were obtained, the characteristics of ground stress were analyzed, which can provide a scientific basis for the layout of tunnel lines and the prediction of rock burst in the surrounding rock. The research showed that the horizontal principal stress of the tunnel increases linearly with the buried depth, and two stress types of thrust stress and strike-slip stress were developed from shallow to deep, respectively. The dominant direction of the maximum horizontal principal stress in the buried depth of the tunnel is consistent with the direction of regional geological tectonic stress, and the angle between the maximum horizontal principal stress and the tunnel strike is less than the optimal angle, which has a certain impact on the stability of surrounding rock. The rock burst risk of surrounding rock increases with the increase of depth, there may be slight rock burst in the surrounding rock at the depth of the tunnel, and relevant measures should be taken to release the ground stress of surrounding rock in time to ensure the construction safety. The research results provide a certain technical reference for the survey, planning, and design of oil and gas pipelines, transportation, and other engineering construction in mountainous areas in the future.
2024, 38(4): 471-476.
doi: 10.3969/j.issn.1007-2993.2024.04.017
Abstract:
Based on the spatial distribution characteristics of karst, the horizontal uneven distribution and vertical zonation characteristics of karst were summarized, and their impact on karst rate statistics was analyzed. Based on the investigation data of a buried sewage plant, the vertical zonation of voids and line karstification rates were analyzed. Furthermore, the probability relationship between the statistical data of borehole porosity rate and liner karst rate was analyzed according to the principle of sampling error. It is considered that the horizontal heterogeneity and vertical zonation of karst development, as while as the actual number of limestone holes and the depth of rock drilled, should be taken into account in each exploration stage. Therefore, the karstification rate is effectively estimated using interval estimation.
Based on the spatial distribution characteristics of karst, the horizontal uneven distribution and vertical zonation characteristics of karst were summarized, and their impact on karst rate statistics was analyzed. Based on the investigation data of a buried sewage plant, the vertical zonation of voids and line karstification rates were analyzed. Furthermore, the probability relationship between the statistical data of borehole porosity rate and liner karst rate was analyzed according to the principle of sampling error. It is considered that the horizontal heterogeneity and vertical zonation of karst development, as while as the actual number of limestone holes and the depth of rock drilled, should be taken into account in each exploration stage. Therefore, the karstification rate is effectively estimated using interval estimation.
2024, 38(4): 477-481.
doi: 10.3969/j.issn.1007-2993.2024.04.018
Abstract:
The engineering risks that may arise from geological conditions mainly include safety risks, quality risks, construction period risks, environmental risks, and investment risks. Geotechnical engineering survey documents should focus on safety and quality risks. The construction methods and procedures of cable tunnels were studied, and various risks during the excavation of shaft support, underground water control in the shaft, and construction of the main body of the tunnel were analyzed. Geological risk identification was carried out based on the engineering geological conditions. It is recommended to establish geological risk lists and develop risk control measures based on the experience of risk control in rail transit.
The engineering risks that may arise from geological conditions mainly include safety risks, quality risks, construction period risks, environmental risks, and investment risks. Geotechnical engineering survey documents should focus on safety and quality risks. The construction methods and procedures of cable tunnels were studied, and various risks during the excavation of shaft support, underground water control in the shaft, and construction of the main body of the tunnel were analyzed. Geological risk identification was carried out based on the engineering geological conditions. It is recommended to establish geological risk lists and develop risk control measures based on the experience of risk control in rail transit.
2024, 38(4): 482-488.
doi: 10.3969/j.issn.1007-2993.2024.04.019
Abstract:
Taking a railway tunnel entrance slope construction site as an example, the slope safety factor at different tunnel entrance elevation, different conditions (slope not excavated, excavation not loaded, loading after excavation), different conditions (natural conditions, rainstorm conditions, earthquake conditions), and different failure modes (internal sliding, multiple sliding, sliding along the contact surface) was studied. The combination of tunnel excavation and slope unloading effectively reduces the slope sliding load, optimizes the design scheme of the treatment project, ensures the safety of the project, and can provide reference for the same type of projects in route selection and slope design.
Taking a railway tunnel entrance slope construction site as an example, the slope safety factor at different tunnel entrance elevation, different conditions (slope not excavated, excavation not loaded, loading after excavation), different conditions (natural conditions, rainstorm conditions, earthquake conditions), and different failure modes (internal sliding, multiple sliding, sliding along the contact surface) was studied. The combination of tunnel excavation and slope unloading effectively reduces the slope sliding load, optimizes the design scheme of the treatment project, ensures the safety of the project, and can provide reference for the same type of projects in route selection and slope design.
2024, 38(4): 489-493.
doi: 10.3969/j.issn.1007-2993.2024.04.020
Abstract:
The underground hidden karst developed in the limestone area has brought great safety hazards to urban engineering construction. Conventional geophysical prospecting methods are difficult to meet the high-precision detection requirements of urban engineering for karst diseases. This research introduced a cross-hole elastic wave CT technology, which can perform high-precision imaging of the underground structure of the engineering site. In combination with other geological data of the site, the shape and scale of the karst in the site area can be accurately predicted. The technology was applied in project practice, and the results show that the elastic wave CT method has achieved accurate identification of underground hidden karst, which is consistent with the geological drilling data.
The underground hidden karst developed in the limestone area has brought great safety hazards to urban engineering construction. Conventional geophysical prospecting methods are difficult to meet the high-precision detection requirements of urban engineering for karst diseases. This research introduced a cross-hole elastic wave CT technology, which can perform high-precision imaging of the underground structure of the engineering site. In combination with other geological data of the site, the shape and scale of the karst in the site area can be accurately predicted. The technology was applied in project practice, and the results show that the elastic wave CT method has achieved accurate identification of underground hidden karst, which is consistent with the geological drilling data.
2024, 38(4): 494-498.
doi: 10.3969/j.issn.1007-2993.2024.04.021
Abstract:
Particle gradation is one of the main factors that affect the mechanical properties of rock-fill materials. To study the mechanical properties and deformation characteristics of the rock-fill materials with single particle size, the large-scale triaxial test and numerical simulation of particle flow were conducted. The main results are as follows: in the case of dense state, the shear contraction of the sample occurs, and the specimen presents the strain hardening model, which shows the opposite rule of the conventional coarse aggregate or sand materials. When the confining pressure is same, and axial strain is identical, the shear contraction of grain with small particle size is more obvious than that of large particle size. When the condition is the same, the deviatoric stress of large particle is larger than small particle's. At the same time, it is found that the particle size of the single graded rockfill materials will have an important influence on its mechanical properties and deformation characteristics.
Particle gradation is one of the main factors that affect the mechanical properties of rock-fill materials. To study the mechanical properties and deformation characteristics of the rock-fill materials with single particle size, the large-scale triaxial test and numerical simulation of particle flow were conducted. The main results are as follows: in the case of dense state, the shear contraction of the sample occurs, and the specimen presents the strain hardening model, which shows the opposite rule of the conventional coarse aggregate or sand materials. When the confining pressure is same, and axial strain is identical, the shear contraction of grain with small particle size is more obvious than that of large particle size. When the condition is the same, the deviatoric stress of large particle is larger than small particle's. At the same time, it is found that the particle size of the single graded rockfill materials will have an important influence on its mechanical properties and deformation characteristics.
2024, 38(4): 499-504.
doi: 10.3969/j.issn.1007-2993.2024.04.022
Abstract:
The commonly used technology of bored piles in sand and pebble fields is mud protection wall rotary excavation or reverse circulation drilling technology. This type of drilling technology requires a large amount of mud and high-quality control, which is prone to quality problems such as collapse and excessive sludge, resulting in single pile bearing capacity not meeting the design requirements. The long spiral drilling and pressure grouting pile technology have no slurry cake and sediment, greatly improving the quality of the pile and the bearing capacity of a single pile. However, for ultra-long piles, the full-length steel cage cannot be used in this progress, which to some extent limits the use of this technology. Based on the experimental research of the Xi'an Olympic Sports Center project, the reinforcement of the entire length was changed to 2/3 of the pile length and not exceeding 25 meters, guaranteeing the use of this method in the project.
The commonly used technology of bored piles in sand and pebble fields is mud protection wall rotary excavation or reverse circulation drilling technology. This type of drilling technology requires a large amount of mud and high-quality control, which is prone to quality problems such as collapse and excessive sludge, resulting in single pile bearing capacity not meeting the design requirements. The long spiral drilling and pressure grouting pile technology have no slurry cake and sediment, greatly improving the quality of the pile and the bearing capacity of a single pile. However, for ultra-long piles, the full-length steel cage cannot be used in this progress, which to some extent limits the use of this technology. Based on the experimental research of the Xi'an Olympic Sports Center project, the reinforcement of the entire length was changed to 2/3 of the pile length and not exceeding 25 meters, guaranteeing the use of this method in the project.
2017, 31(3): 153-159,163.
doi: 10.3969/j.issn.1007-2993.2017.03.010
摘要：
将边坡稳定性分析的方法分为确定性分析方法(以瑞典圆弧法、简化Bishop法等为代表的极限平衡法和以有限元法、有限差分法等为代表的数值分析方法)和非确定性方法(可靠度法、模糊综合判断法、灰色系统法、人工智能法等),详述了各分析方法的原理、优缺点以及适用性,并对其中一些方法进行了比较分析,提出了岩土边坡系统稳定性评价的发展方向。
将边坡稳定性分析的方法分为确定性分析方法(以瑞典圆弧法、简化Bishop法等为代表的极限平衡法和以有限元法、有限差分法等为代表的数值分析方法)和非确定性方法(可靠度法、模糊综合判断法、灰色系统法、人工智能法等),详述了各分析方法的原理、优缺点以及适用性,并对其中一些方法进行了比较分析,提出了岩土边坡系统稳定性评价的发展方向。
2020, 34(3): 143-149.
doi: 10.3969/j.issn.1007-2993.2020.03.005
摘要：
有限元软件数值模拟是现在从业人员分析敏感环境下基坑工程的重要手段，选择合适的本构模型是其关键。为了解工程中常用的三种土的本构模型适宜性，运用三维有限元软件Midas GTS NX模拟了某大型深基坑开挖过程，将采用不同本构模型的数值模拟结果与基坑监测结果进行对比，进而分析本构模型的适用性。可为本区类似工程进行有限元数值模拟分析时提供参考和借鉴。
有限元软件数值模拟是现在从业人员分析敏感环境下基坑工程的重要手段，选择合适的本构模型是其关键。为了解工程中常用的三种土的本构模型适宜性，运用三维有限元软件Midas GTS NX模拟了某大型深基坑开挖过程，将采用不同本构模型的数值模拟结果与基坑监测结果进行对比，进而分析本构模型的适用性。可为本区类似工程进行有限元数值模拟分析时提供参考和借鉴。
2016, 30(2): 85-88.
doi: 10.3969/j.issn.1007-2993.2016.02.007
摘要：
BIM技术具有三维可视化、碰撞检测、工程信息管理等众多特点,极大地提升了工程质量与效率,在建筑领域得到迅猛发展,然而在岩土工程中因为收费机制、软件功能限制、应用局限性等原因导致其发展的严重滞后。随着设计可视化、信息化发展进程,BIM也将在岩土中得到立足。对BIM在岩土中的应用现状进行了剖析,并对发展前景展望。以武汉亚洲医院基坑项目为依托,进行了BIM的完整实施,探讨了模型建立方式与施工应用方法,对今后BIM在岩土工程中的应用推广具有一定指导意义。
BIM技术具有三维可视化、碰撞检测、工程信息管理等众多特点,极大地提升了工程质量与效率,在建筑领域得到迅猛发展,然而在岩土工程中因为收费机制、软件功能限制、应用局限性等原因导致其发展的严重滞后。随着设计可视化、信息化发展进程,BIM也将在岩土中得到立足。对BIM在岩土中的应用现状进行了剖析,并对发展前景展望。以武汉亚洲医院基坑项目为依托,进行了BIM的完整实施,探讨了模型建立方式与施工应用方法,对今后BIM在岩土工程中的应用推广具有一定指导意义。
2016, 30(1): 6-11.
doi: 10.3969/j.issn.1007-2993.2016.01.002
摘要：
探讨了BIM在岩土工程勘察领域应用的可行性,根据多年的研究和工程实践,提出了BIM技术应用于岩土工程勘察领域的目标、实现途径和分阶段的解决方案。
探讨了BIM在岩土工程勘察领域应用的可行性,根据多年的研究和工程实践,提出了BIM技术应用于岩土工程勘察领域的目标、实现途径和分阶段的解决方案。
3D Laser Scanning Technology and BIM Technology in Ancient Building Protection Surveying and Mapping
2019, 33(4): 222-225.
doi: 10.3969/j.issn.1007-2993.2019.04.008
摘要：
结合北京市密云区古北口村文物建筑群工程实例介绍了三维激光扫描技术、BIM（建筑信息模型）在古建筑测绘中的应用。通过对比传统测绘方法，证明其在测绘及文物保护方面应用的优势。
结合北京市密云区古北口村文物建筑群工程实例介绍了三维激光扫描技术、BIM（建筑信息模型）在古建筑测绘中的应用。通过对比传统测绘方法，证明其在测绘及文物保护方面应用的优势。
2016, 30(1): 12-19,38.
doi: 10.3969/j.issn.1007-2993.2016.01.003
摘要：
黄土丘陵沟壑区高填方工程的地形地貌和地质环境复杂,场地内常分布有大面积湿陷性黄土和淤积土,且具有土方量大、影响因素多、施工工期紧、沉降控制要求高等特点,建设过程面临着填方体的稳定、变形、排水、湿化变形控制及边坡防护等问题。以国内几处典型黄土高填方工程为例,介绍了通过场地综合地质条件评价、土方平衡优化、地下盲沟排水、原地基强夯加固处理、填筑体压(夯)实处理、填挖边坡防护处理、施工质量立体式监控、岩土工程全程监测等多种手段有效组合,解决黄土高填方工程问题的实践工作,相关经验可供类似工程借鉴。
黄土丘陵沟壑区高填方工程的地形地貌和地质环境复杂,场地内常分布有大面积湿陷性黄土和淤积土,且具有土方量大、影响因素多、施工工期紧、沉降控制要求高等特点,建设过程面临着填方体的稳定、变形、排水、湿化变形控制及边坡防护等问题。以国内几处典型黄土高填方工程为例,介绍了通过场地综合地质条件评价、土方平衡优化、地下盲沟排水、原地基强夯加固处理、填筑体压(夯)实处理、填挖边坡防护处理、施工质量立体式监控、岩土工程全程监测等多种手段有效组合,解决黄土高填方工程问题的实践工作,相关经验可供类似工程借鉴。
2019, 33(2): 115-120.
doi: 10.3969/j.issn.1007-2993.2019.02.013
摘要：
针对珠海地区的深厚软基，采用真空联合堆载预压法进行加固处理。在施工过程中对软基的地表沉降、膜下真空度、孔隙水压力、深层水平位移等进行监测，得到了真空预压加固软土地基的随时间变化曲线。软基处理完成后对原状土进行原位十字板剪切试验和载荷试验，并取土进行室内土工试验。监测和检测试验分析表明：加固后土的物理力学性质有了明显提高，地基加固效果较好，其影响深度达到25～30 m，在15～20 m范围内加固效果最为显著; 但真空预压并未改变软土的触变性，加固后的软土仍应避免扰动。
针对珠海地区的深厚软基，采用真空联合堆载预压法进行加固处理。在施工过程中对软基的地表沉降、膜下真空度、孔隙水压力、深层水平位移等进行监测，得到了真空预压加固软土地基的随时间变化曲线。软基处理完成后对原状土进行原位十字板剪切试验和载荷试验，并取土进行室内土工试验。监测和检测试验分析表明：加固后土的物理力学性质有了明显提高，地基加固效果较好，其影响深度达到25～30 m，在15～20 m范围内加固效果最为显著; 但真空预压并未改变软土的触变性，加固后的软土仍应避免扰动。
2017, 31(6): 306-310.
doi: 10.3969/j.issn.1007-2993.2017.06.009
摘要：
以某一地下一~二层连通车库基坑设计项目为依托,在分析该基坑工程特点的基础上,介绍和分析了不同开挖深度和复杂环境条件下的多种基坑支护形式的组合应用和监测结果,为今后类似工程提供一些借鉴和参考。
以某一地下一~二层连通车库基坑设计项目为依托,在分析该基坑工程特点的基础上,介绍和分析了不同开挖深度和复杂环境条件下的多种基坑支护形式的组合应用和监测结果,为今后类似工程提供一些借鉴和参考。
2019, 33(2): 84-88.
doi: 10.3969/j.issn.1007-2993.2019.02.006
摘要：
总结分析了建筑工程肥槽回填土质量不良引发的常见工程问题，以及肥槽回填土不易施工密实的几个主要原因，并总结提出了各种肥槽回填土处理方法，以及它们主要的适用条件。
总结分析了建筑工程肥槽回填土质量不良引发的常见工程问题，以及肥槽回填土不易施工密实的几个主要原因，并总结提出了各种肥槽回填土处理方法，以及它们主要的适用条件。
2018, 32(4): 189-193,198.
doi: 10.3969/j.issn.1007-2993.2018.04.006
摘要：
上海市城市道路发生的地面塌陷主要原因为浅部砂层分布区域地下排水管线渗漏引发流砂,导致地下土体流失,地表硬壳层承载力下降。将有限元和离散元二者进行耦合,从管线渗漏位置和对邻近管线影响两个方面诱发地下空洞机理进行数值模拟研究。研究结果表明,管道表面顶部局部渗漏引起地表以下土体流失量最大,底部渗漏造成的影响范围较小;管道断裂渗漏引起的地面塌陷范围比管道局部渗漏大得多,但深度较管道顶部局部渗漏引起的塌陷深度小;邻近管道埋深越大,地表以下土体流失量越大,引起塌陷影响区域范围越大,而埋深较浅时,其所受邻近渗漏管道的影响较大;在对地面塌陷进行监测与预防时,不应仅关注地表沉降变形,关注管道周边的土体变形是一种更加及时有效的方法。
上海市城市道路发生的地面塌陷主要原因为浅部砂层分布区域地下排水管线渗漏引发流砂,导致地下土体流失,地表硬壳层承载力下降。将有限元和离散元二者进行耦合,从管线渗漏位置和对邻近管线影响两个方面诱发地下空洞机理进行数值模拟研究。研究结果表明,管道表面顶部局部渗漏引起地表以下土体流失量最大,底部渗漏造成的影响范围较小;管道断裂渗漏引起的地面塌陷范围比管道局部渗漏大得多,但深度较管道顶部局部渗漏引起的塌陷深度小;邻近管道埋深越大,地表以下土体流失量越大,引起塌陷影响区域范围越大,而埋深较浅时,其所受邻近渗漏管道的影响较大;在对地面塌陷进行监测与预防时,不应仅关注地表沉降变形,关注管道周边的土体变形是一种更加及时有效的方法。
2021, 35(4): 269-274.
doi: 10.3969/j.issn.1007-2993.2021.04.012
Abstract:
2021, 35(1): 1-6,11.
doi: 10.3969/j.issn.1007-2993.2021.01.001
Abstract:
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Science & Technology Information Network of Geotechnical Engineering of National Defence & Machinery Industry; China Ordance Industry Survey and Geotechnical Institute Co., Ltd.
ISSN：1007-2993
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