岩土工程技术

Research on Bearing Capacity of Mudstone Foundation Based on the Improved Rock Loading Test

Ling Xiao, Luo Kang, Zhang Lianhua

2017, 31(1): 1-4,54. doi: 10.3969/j.issn.1007-2993.2017.01.001

[Abstract](57) [PDF 1643KB](13)

Abstract:
In order to simulate the effect of edge loads on the bearing capacity of mudstone,improved rock plate loading test and carried out four pilot sites weathered mudstone rock loading test on a project site in Chengdu Tianfu new area and obtain the corresponding p-s curves.Experiments show that:①Under the condition of applying 200 kPa edge loads,the bearing capacity of mudstone has the 0.7 to 0.9 times increase compare with applying no edge loads,there needs to have the modification of depth for mudstone.Also try to get an appropriate depth modified coefficient in this paper.②Combining the rock loading test results with the results of indoor rock uniaxial compressive strength test,to do inverse computation of reduction factor according to the standard method which draw the conclusion that the value of the standard proposal is conservative.When the bearing capacity of mudstone in Chengdu is determined by the uniaxial compressive strength test,the value of reduction factor could be improved appropriately.

Automatic Detection of Rock Mass Discontinuity Trace Based on Digital Image Processing

Kuang Jie, Zhang Yangsong

2017, 31(1): 5-8,13. doi: 10.3969/j.issn.1007-2993.2017.01.002

[Abstract](59) [PDF 5520KB](8)

Abstract:
A new methodology was presented for automatic detection of rock mass discontinuity trace.Based on edge detection and filter of characteristic,using of the differences of specific mathematical features on the connected pixel region between discontinuity information and non-discontinuity noise,non-discontinuity noise was filtered out and discontinuity information was left by this new methodology.Then,the discontinuity traces were detected automatically.Taking the image of rock mass discontinuity in Beishan for example,the image was processed in MATLAB by this methodology.The results showed that for a large variety of complex discontinuity image,the methodology can quickly and accurately detect the trace of rock mass discontinuity automatically.

Spring of Cold Region Influence on Expansive Soil Cut Slope Stability Analysis

Li Yong

2017, 31(1): 9-13. doi: 10.3969/j.issn.1007-2993.2017.01.003

[Abstract](42) [PDF 5559KB](6)

Abstract:
Combined with the actual situation in the construction of a railway project in the north of China,this paper expounds the correlation analysis of the area expansion soil engineering properties and cutting slope failure mode,for local district spring thaw characteristics,analyzes the new excavation by the spring thaw induced expansive soil slope failure mechanism.At the same time,the relationship between climate change and slope collapse is analyzed,with the consideration of spring melt characteristics of expansive rock slope stability calculation method,puts forward the reasonable engineering measures and suggestions.It has certain guiding significance to the construction of similar areas.

The Static Triaxial Test Study of Two Kinds of Asphalt Concrete Specimens under Different Cell Pressure

Zou Yuqiang, Xing Xinfu

2017, 31(1): 14-17,31. doi: 10.3969/j.issn.1007-2993.2017.01.004

[Abstract](39) [PDF 2617KB](6)

Abstract:
In order to study the sample preparation method and influence of cell pressure on mechanical properties of asphalt concrete specimens,two sample preparation methods conducted for asphalt concrete specimens and four group triaxial tests with different cell pressure analyzed respectively in this paper.It concludes that,the higher cell pressure results in higher failure strength of asphalt concrete,and also leads to lower sample dilatancy.Compared with indoor simulation drilling sample,the peak intensity of compaction shaping sample is higher in（σ₁-σ₃）-ε₁ curve,the initial tangent modulus is greater,the phenomenon of shear dilatancy is more obvious.Fitting the test curve with Duncan-Chang model,indicated that the fitting effect of Duncan-Chang model on the stress-strain of asphalt concrete is not well,and Duncan-Chang model can not be simulated accurately to reflect dilatancy and softening phenomenon of asphalt concrete as well.

Comparison Method of Density Meter Method and Pipette Method in Determining the Content of Clay

Wang Lu, Jiang Baikun

2017, 31(1): 18-20,40. doi: 10.3969/j.issn.1007-2993.2017.01.005

[Abstract](51) [PDF 440KB](8)

Abstract:
Make standand samples after drying,crushing and sieving the samples which are from the new airport project.In the condition of the same ambient temperature,the same dispersant,and the same single test dose,make contrast experiments by using density meter and pipette method,respectively.According to compare the results by using the two different methods,the content of clay of both methods are nearly equal.It is proved that pipette method has more advantages on smaller error and slighter agitation to suspension.

Research on the Soil Pressure Distribution of the Pile-Anchor Supporting Structure in Clay

Ren Jun, Xu Chao, Yin Wenbiao

2017, 31(1): 21-25. doi: 10.3969/j.issn.1007-2993.2017.01.006

[Abstract](34) [PDF 1851KB](9)

Abstract:
The pile-anchor supporting structure with its low technical requirements and wide applicability has been highly received by the design and construction units.But the current practice of geotechnical engineering remained ahead of theory,the progress of technology must put forward higher design requirements on foundation pit.Analysis of a deep foundation pit in Shunyi district by FLAC^3D,simulate the curve of soil pressure distribution.Compared with the classical soil pressure theory,the displacement of the pile,the tension of the anchor is close to the measured value.The simulate curve of soil pressure distribution accord with engineering practice more.In this paper,the research of the soil pressure distribution in silty clay is very important for optimizing the structure design and reducing the construction cost.

The Monitoring Technology of Shallow Buried Tunnel Construction

Zhang Fulong, Wang Fengcang, Zhang Xiaoqiang

2017, 31(1): 26-31. doi: 10.3969/j.issn.1007-2993.2017.01.007

[Abstract](48) [PDF 1798KB](7)

Abstract:
The deformation of surrounding rock of shallow buried tunnel construction is complex,the vertical displacement of the tunnel vault is selected as the research object to analyze the monitoring method of vertical displacement of surrounding rock of shallow buried tunnel section,the field monitoring is conducted in Alatan tunnel,and the finite element numerical model is established,and the shallow buried tunnel surrounding rock deformation law is analyzed.The results show that within the scope of 0.6 times the hole diameter excavation had a greater influence on the vertical displacement of vault surrounding rock,it is up to 61%-67% of total displacement;Compared with 75 m within the scope of the vertical displacement,the vertical displacement is almost zero at the distances from 1.2 times the center of the tunnel hole diameter,the surrounding rock loose circle extends to the surface,the farther from the center line of the tunnel,the less disturbance intensity.The strata and surface variation law of numerical calculation are basicly consistent with the field measured.

Application of Landing Rectifying Inclination and Grouting Reinforcement Technique in Some Small Engineering of Beijing

Liu Xuanpeng, Guo Yongsheng, Qin Guodong

2017, 31(1): 32-36. doi: 10.3969/j.issn.1007-2993.2017.01.008

[Abstract](29) [PDF 2302KB](7)

Abstract:
Aimed at the integrated pump room and underground pool in Beijing some project,floated up due to the surface water level rise abruptly in heavy rain weather,using the landing rectifying inclination and grouting strengthening technology for processing.Through the geological radar detection and deformation monitoring,the foundation of the integrated pump room and underground water meet the requirements of normal using after processing.

The Study of Deriving Orthophoto Maps Based on the UAV X100 Aerophotogrammetry

Gui Weizhen, Yin Yanyun, Cao Minglan

2017, 31(1): 37-40. doi: 10.3969/j.issn.1007-2993.2017.01.009

[Abstract](33) [PDF 3583KB](5)

Abstract:
In recent years,the technique of aerophotogrammetry based on the unmanned aerial vehicle has developed rapidly.Based on a sample of the UAV X100 application in the low altitude photogrammetry,this paper studies the technique from several aspects,such as UAV field data collection,image mosaic,derived orthophoto maps,3D graph display and so on,which demonstrates the advantage of deriving orthophoto maps by the UAV X100.

Research on the Influence of Deep Erosional Paleochannel Foundation Soil to the Engineering Construction in Coastal Areas

Zhou Yuming, Wen Weiguang, Liu Xiaolei

2017, 31(1): 41-44. doi: 10.3969/j.issn.1007-2993.2017.01.010

[Abstract](35) [PDF 1707KB](8)

Abstract:
Based on the analysis of the Quaternary geological survey data in coastal areas,using the drilling data of engineering investigation as a means of verification,we have ascertained the spatial distribution of some deep erosional paleochannel in the late Pleistocene to mid Holocene in coastal areas,and speculated on itshistorical origin;Combined with the special engineering geological characteristics and hydrogeological characteristics of the deep erosional paleochannel,we analyzed the adverse effects on the engineering construction.

Drilling Technology and Exploration Evaluation in the Geothermal Well Construction in the Guozijian Region,Beijing

Qian Kaizhu, Lin Ye, Chang Tiesen

2017, 31(1): 45-48. doi: 10.3969/j.issn.1007-2993.2017.01.011

[Abstract](30) [PDF 1112KB](8)

Abstract:
As a new type of renewable energy,geothermal resources can solve the contradiction between economic development and environmental protection in Beijing.After scientific and reasonable investigation,designation and construction,the JR-181 geothermal well has been successfully completed.In the processing of construction,successful treatments of drill pipe fracture,drill tool sticking,well blocking with collapse and the small amount of water yield,it ensured the drilling to be processed on schedule.The depth of well is 3700.88 m,the well yield per day is 519.18 m³,the temperature of water is 69.3 ℃.With these conditions,the JR-181 geothermal well has been evaluated as high-quality geothermal well.This project has end up the history that there is no geothermal well in the Guozijian region,Beijing.In addition,it plays an positive role to promote geothermal resources development in Beijing.

Study on Surface Subsidence Law and Control Measures in Large Section Rectangular Pipe Jacking Method in Complex Environment

Zhu Jian, Li Zhenyong, Zhang Long

2017, 31(1): 49-54. doi: 10.3969/j.issn.1007-2993.2017.01.012

[Abstract](65) [PDF 2318KB](11)

Abstract:
In order to study regularity and control measures of surface settlement during shallow large cross-section(6.9 m×4.9 m) rectangular pipe-jacking construction in the north second terrace area of Yongjiang river.The paper based on No.3 exit project of Jinhuguangchang station on Line 1 of Nanning Metro,three-dimensional model is set up by finite difference software FLAC3D to simulate pipe jacking construction process,and compared with actual monitoring results.Conclusions are drawn as follows:①the main disturbance range of soil in front of Pipe jacking machine is about 2 times of the tunnel width;②the surface transverse settlement curve presents normal distribution as the center of pipe axis,the impact range of surface transverse settlementis about 3 times of the tunnel width;③in order to ensure that the surface uplift and settlement are within the range of reasonable control through the pipe jacking head up slightly,add grouting sleeve plate,pipe section antifriction slip casting and reasonable jacking parameters.

2017 Vol. 31, No. 1