岩土工程技术

Application of the Monitoring and Measuring Technologies in Constructing the Henglong Mountain Tunnel

Xiao Yuchun

2012, 26(5): 217-221. doi: 10.3969/j.issn.1007-2993.2012.05.001

[Abstract](22) [PDF 679KB](4)

Abstract:
The Henglong mountain tunnel of Fulong Expressway was constructed by New Austrian Tunneling Method(NATM). This article not only introduced the monitoring and measuring technology of construction on displacement of surrounding rock and the change of stress by mouth of a horn part of the super large section in the Henglong mountain tunnel, but also introduced the timely adjustment of supporting system design parameters such as tunnel prestressed rock bolt according to the monitoring and measurement analysis of treatment results in this project. Results showed that careful monitoring and analysis of the construction work play a key role not only in ensuring the tunnel construction safety and the economic and reasonable supporting, but also in obtaining reliable design parameters.

The Establishment of the Deformation Monitoring Forecast System on the Expressway Through Goaf Based the Hyperbolic Model

Kang Jinming, Jing Zhaoji

2012, 26(5): 222-225. doi: 10.3969/j.issn.1007-2993.2012.05.002

[Abstract](24) [PDF 712KB](5)

Abstract:
Through the deformation monitoring of the mined-out area highway subgrade subsidence,established the embankment settlement database. and based on the survey datas, The author established the deformation forecast model of surface subsidence, research and developed the subgrade deformation monitoring forecast system, analysed the settlement remaining of highway subgrade deformation and created the settlement prewarning report.

Application of Gross Error in the Dock Cofferdam Construction Safety Monitoring

Zhou Yuan, Peng Manhua, An Xiaorui

2012, 26(5): 226-229,255. doi: 10.3969/j.issn.1007-2993.2012.05.003

[Abstract](11) [PDF 694KB](4)

Abstract:
The monitoring data of dock cofferdam is very important in the construction of dock. However, some incorrect factors led to the monitoring data does not match the actual situation. while the abnormal value can not be intuitive removed, thus it has a great impact on dock cofferdam construction safety monitoring, So it must be judged and handled. This article introduced 3σ, Grubbs and Dixon methods to handle the Gross Error, and applied them to the concrete dock cofferdam construction safety monitoring. The results showed that these methods which provide help to the dock cofferdam construction. They can quickly, easily and effectively handle the abnormal value in some degree.

Dynamic Compaction Ground Rreatment Study on Vibration Effects

Wu Xingye, Xu Mingming, Wu Qiong

2012, 26(5): 230-233,251. doi: 10.3969/j.issn.1007-2993.2012.05.004

[Abstract](19) [PDF 921KB](7)

Abstract:
The method of dynamic compaction is one of important methods for ground treatment, the dynamic compaction to evaluation of dynamic compaction vibration effect, the basis of the evaluation are dynamic. This article takes the Changping District ridge village site as an example, through the landfill site for dynamic compaction vibration monitoring, analysd the dynamic compaction vibration amplitude and attenuation law of frequency, and the four polynomial representation field medium attenuation index. In field medium action spectra and dynamic excitation spectra based on, obtained by calculating the dielectric function and dynamic excitation function. Through the continuous accumulation of dynamic compaction vibration data, set up different properties of rock and soil and ground medium function relationship, then clearly engineering rock soil physical and mechanical properties and the dynamic performance between constitutive relation.

The Understanding About Foundation Settlement of Existing Buildings Caused by Foundation Pit Dewatering in Jinan

Fan Huchuan, Yu Feng

2012, 26(5): 234-237. doi: 10.3969/j.issn.1007-2993.2012.05.005

[Abstract](23) [PDF 712KB](8)

Abstract:
Combined with engineering experience,make a summary to influencing factors about foundation settlement of existing buildings caused by foundation pit dewatering.Aimed at the problem that compressibility in additional stress segment can not be accurately taken in estimating foundation settlement caused by foundation pit dewatering by layer-wise method, propose the method based on formation stress history to estimate foundation settlement caused by foundation pit dewatering,while combining with engineering example,make a prediction for composite foundation settlement caused by foundation pit dewatering.

Groundwater Recharge of Pit Dewatering Close to the Metro

Ju Chengsong, Xu Dan

2012, 26(5): 238-241. doi: 10.3969/j.issn.1007-2993.2012.05.006

[Abstract](32) [PDF 906KB](9)

Abstract:
During the foundation pit dewatering process, groundwater recharge is taken as the pit water level reduced in pit in order to protect the safety of the environment to ensure that the water level drop smaller within a certain area outside the pit.The grand international financial center is located at the junction of three subway, environmental protection is higher.Groundwater recharge technology combined with dewatering can control dewatering sphere of influence, by the numerical method to calculate and analysis of the recharge, and successfully applied in practical engineering.

The Variable Rigidity for Balance Settlement Design of Pile Foundation and the Application in Project

Le Yuan, Yu Wei, Wang Dong

2012, 26(5): 242-246,258. doi: 10.3969/j.issn.1007-2993.2012.05.007

[Abstract](24) [PDF 878KB](7)

Abstract:
By the contrast of the old and the new technical code for building pile foundations,the principles of variable rigidity design is presented to solve high-rise building problems induced by variational elevation uneven loading distributing and short of bearing stratum in site.Based on variable rigidity, the optimum design method for balance settlement is proposed for promoting settlement uniformity.It is proved that the proposed idea can reduce the differences in settlement and raft the internal forces, optimize the pile program, cost savings, access to economic benefits in the actual high-rise building designs.

Analysis of Formation Mechanism and Prevention Measures of Lijiawuji Collapse

Yi Zhenhua

2012, 26(5): 247-251. doi: 10.3969/j.issn.1007-2993.2012.05.008

[Abstract](28) [PDF 978KB](4)

Abstract:
Collapse on the steep slope is one of the frequent geological hazards in southwest region,which is mostly controlled by the combination of joints and structural surfaces in rock mass. Based on the investigation of the engineering geological conditions of Lijiawuji collapse area,This article described the deformation characteristics of dangerous rock mass,and analyzed its formation mechanism and failure mode,then the stability of dangerous rock mass was evaluated, and finally the Treatment is given prevention measures as well.

Study on Lateral Unlaoding of Tianjin Soft Dredger Soil by True Triaxial Text

Wang Tulong, Li Zuoliang, Gao Xuemi

2012, 26(5): 252-255. doi: 10.3969/j.issn.1007-2993.2012.05.009

[Abstract](22) [PDF 688KB](5)

Abstract:
In order to conduct the research on deformation properties of unloading of pit excavation,a series of true triaxial tests were performed in tianjin soft dredger fills under the condition of unconsolidated-undrained with rigid-flexible composite true triaxial apparatus, it keeps that major principle stress fixed and intermediate principal strain ε₂≈0 and minor principle stress decreased. The results indicated that tangent compression modulus increases with increasing of compression stress, stress-strain relation ε₁ and ε₃ is linearity, poisson ratio is not match with classical soil mechanics theory,μ₃₁>0.5 and increases with increasing of compression stress, pore water pressure increases at first then decreases.

The Discussion of Dispersing Pressure of Prestressed Anchor Cable Tensioning Test and Stress Loss

Zuo Xiaowei, Zhou Feng

2012, 26(5): 256-258. doi: 10.3969/j.issn.1007-2993.2012.05.010

[Abstract](33) [PDF 628KB](6)

Abstract:
As site monitoring the tension of dispersing pressure prestressed anchor cable of a solpe enginneering.This article introduced the reinforcement mechanism of dispersing pressure prestressed anchor. Further monitor and analyse the stress loss and the anchor elongation.

The Carrying Capacity Analysis of Kunming New Airport Terminal Area Underlying Cave Foundation

Deng Jiewen, Peng Dalei, Liu Hong

2012, 26(5): 259-262,271. doi: 10.3969/j.issn.1007-2993.2012.05.011

[Abstract](18) [PDF 808KB](6)

Abstract:
There are many factors that affect bearing capacity of Cave foundation, such as Cave depth, the caves diameter (span), spacing vertically adjacent caves and caverns section form the foundation bearing capacity. The way, combined engineering geology analysis with numerical simulation, was applied to analyze the underlying bearing capacity of Cave foundation. According to this way, it concludes that the relationship between the diameter of the upper load and the lower part of the dissolution is smaller when a single cave depth is greater than 2 times, and the impaction of the cave to the top load can be ignored when the spacing of the level of the adjacent cave is greater than one times and the vertical distance is greater than 0.5 times of the span. Besides, the upper part of the maximum load q_max decrease about 6% to 10% from each additional 5% of dissolution rate. When the span is greater than three times of the hole high, the decrease range of the maximum load on the top of foundation is relatively small; on the contrary, the load that vertical type caves can withstand is relatively large.

The Distribution Characteristics and Research on the Alluvial Soil in Changzhou

Xia Yunjuan, Wei Tingzhong

2012, 26(5): 263-266. doi: 10.3969/j.issn.1007-2993.2012.05.012

[Abstract](20) [PDF 741KB](5)

Abstract:
The alluvial soil is widely distributed in the main city of Changzhou, whose existence will not be conducive to engineering construction. Understanding and grasping the causes and distribution of the alluvial soil could provide guidance of sing the appropriate means of investigation and reasonable layout survey workload to determine the safe and economical and reasonable foundation plan in geological exploration.

The Application of the Bracing Engineering for Timeliness Effect of Swelling Rock on Deep Foundation

Xu Jianhua, Zhu Zhen, Feng Jianghong

2012, 26(5): 267-271. doi: 10.3969/j.issn.1007-2993.2012.05.013

[Abstract](35) [PDF 712KB](6)

Abstract:
Research of the projecting feature depending on swelling rock physical and mechanical characteristics and the engineering characteristics. The characteristics bracing engineering of deep foundation pit combined with substructure. Look for relations of decay period and safe period, the timeliness effect was put forward by their relational, For this to made economic effect design methodology. A Case Study of Nanning, which was testified further by the timeliness effect of bracing engineering of deep foundation pit on swelling rock.

2012 Vol. 26, No. 5