岩土工程技术

Application and Research of Rock Socketed Retaining Piles for Deep Foundation Pit with Micro Steel Tube

Wu Qingsong, He Xingliang, Jiang Dawei

2017, 31(6): 271-273,288. doi: 10.3969/j.issn.1007-2993.2017.06.001

[Abstract](48) [PDF 700KB](9)

Abstract:
Based on the foundation pit bracing for a particular red clay site on karst region in Guilin,with a limited retaining piles condition, proposed a method that the soil layer using reinforced concrete row piles while rock layer adopting micro steel tube pile, which can avoid the end-suspended piles, accelerate construction speed and save cost; starting from the forces analysis,check the bending stress and shear stress using section modulus equivalent and section area equivalent approach respectively,analyzing the displacement monitoring result of micro steel tube retaining pile. The research shows that soil layer using reinforced concrete row piles while rock layer adopting micro steel tube pile is feasible, which can effectively control the foundation displacement.

Study on the Possibility of Liquefaction of Sand Cushion in Immersed Tunnel

Wang Xiaowei

2017, 31(6): 274-277,293. doi: 10.3969/j.issn.1007-2993.2017.06.002

[Abstract](35) [PDF 1139KB](7)

Abstract:
Based on the test for dynamic modulus of elasticity and test for resistance to liquefaction and seismic performance are analyzed, so as to obtain the shear stress distribution and the distribution of pore water pressure of 0. 6 m thickness;sand pressing method; sand cushion under earthquake loading, combined with sand-sand cushion dynamic modulus and damping ratio test results of liquefaction strength with the move,estimate the anti liquefaction pressure sand sand cushion method, this method has very good practical value.

Deep Hole Dynamic Compaction Method Dealing with Big Thickness of High Slope Collapsible Loess in the Application of a Transformer Substation Project Down-Hole Dynamic Compaction Research

Ma Junping

2017, 31(6): 278-282. doi: 10.3969/j.issn.1007-2993.2017.06.003

[Abstract](55) [PDF 18010KB](8)

Abstract:
China's loess wide distribution, collapsible soil thickness from a few meters to dozens of meters, according to the characteristics of the traditional engineering foundation treatment methods adopted by cushion method, dynamic consolidation method, compaction method, grouting method, foundation method can deal with the traditional treatment and can meet the thickness requirements. And meet the requirements of bearing capacity, while the deep hole dynamic compaction method can also meet the above requirements. The author of a design, gravity wet deep strong in a 750 kV substation engineering foundation treatment of loess site by the consolidation of the composite foundation construction and treatment effect test study to conduct a comprehensive analysis, and put forward relevant proposals.

Engineering Case of Comparison on Self-balanced Pile Testing Method and Anchored Pile Method

Zhang Xianlin

2017, 31(6): 283-288. doi: 10.3969/j.issn.1007-2993.2017.06.004

[Abstract](53) [PDF 1632KB](13)

Abstract:
The self-balanced pile testing method is a new axial static load test of pile. Compared with the traditional static load test method to save time labor and costs. Through the same type of test piles in a project, static load test and uplift test are carried out by self-balanced pile testing method and anchored pile method, respectively. The test results show the feasibility of self-balanced pile testing method.

The Research on Test Method of Laboratory Subgrade Coefficient

Zhang Junjie, Guo Zhen, Zhang Lihong

2017, 31(6): 289-293. doi: 10.3969/j.issn.1007-2993.2017.06.005

[Abstract](43) [PDF 565KB](8)

Abstract:
Coefficients of subgrade reaction on Ningbo soft soil within the range of metro tunnels excavation were worked out through the way of consolidation tests and triaxial test,and the correction formula of laboratory subgrade coefficient that applicable to Ningbo soil was calculated out by contrasting with experimental results and normative empirical values. Then the standard subgrade coefficient of different foundation soil was got after being amended of the calculation formula, verifying the validity of test method of laboratory subgrade coefficient and solving the problems of determination of batch subgrade coefficient. It can be used for engineering design and construction.

Properties Analysis of the Continuous Wall Encountering the Sewage Pipe

Huang Weida

2017, 31(6): 294-297. doi: 10.3969/j.issn.1007-2993.2017.06.006

[Abstract](38) [PDF 784KB](8)

Abstract:
While the underground continuous wall of a foundation pit encounters the sewage pipe,the wall need to break off, and the opening produces. To solve the above problems, the paper uses the method of the soil reinforcement and the pile combination, and the soil arch forms between the piles for stress transfer and isolation. By using the finite element, the soil deformation and internal force characteristics of piles are analyzed in detail. The conclusion is that the pile number and soil reinforcement width is the key role to control the soil deformation, and the deformation is smaller along with the greater the scope of consolidation. The measured data shows that the displacement of the opening region in underground continuous wall is less than the calculated value, and the results can be referred to similar projects.

Influence on Deformation and Internal Force of Retaining Wall Induced by Prestress of Strut

Liu Bo, Li Jiesan

2017, 31(6): 298-302,310. doi: 10.3969/j.issn.1007-2993.2017.06.007

[Abstract](30) [PDF 1191KB](9)

Abstract:
The prestressed strut has a firm control over the deformation of foundation pit, but a consensus about the regularity of the influence on deformation of foundation pit which is induced by prestress of strut has not been obtained. In order to compare the effects of different prestress schemes, a two-dimensional finite difference software named FLAC is adopted to analyze the foundation pits where the struts is prestressed. By comparing the additional displacement and moment of the retaining wall induced by the prestress of different prestress schemes and on different stages in excavation, it is found that additional displacement and moment of the retaining wall induced by the prestress remains the same on different stages in excavation. The effect of the prestress in several struts functioning simultaneously is equal to the sum of effect of each prestress functioning alone and the additional displacement and moment of the retaining wall is proportional to the size of prestress. The effect on retaining wall induced by prestress is mainly controlled by its relative position to the retaining wall.

Research on Deformation of Deep Foundation Pit Supporting Structure

Luo Kang, Zheng Yuhui, Xu Jing

2017, 31(6): 303-305,316. doi: 10.3969/j.issn.1007-2993.2017.06.008

[Abstract](128) [PDF 1913KB](11)

Abstract:
Based on the deep foundation pit engineering in Chengdu as an example,using two kinds of present main foundation pit design calculation software combine with massive local test and monitor data which obtains a conclusion that the basement deformation of gravel layer and intermediary weathered mudstone cannot take default value of 10 mm but between 3~4 mm. The method that calculate deformation, upper gravel layer should use m-value and k-value should be used for mudstone that can make the calculation result and actual deformation match. This research has an important guiding significance to engineering construction.

Combined Application of Multiform Retaining Structures in Deep Foundation Pits

Wei Renjie

2017, 31(6): 306-310. doi: 10.3969/j.issn.1007-2993.2017.06.009

[Abstract](161) [PDF 6274KB](20)

Abstract:
Based on the analysis of the characteristics of a deep foundation pit about a connected garage,the combined application of multiform retaining structures and monitoring results with different excavation depth and complicated environment are introduced and analyzed. It would provide a good reference to other similar projects.

Application of Low-cost Unmanned Aerial Vehicle in 3D Modelling of Large Scale Geotechnical Engineering:Case Study of High Filling Engineering of Airport in Mountain Area of Southwest China

Wu Zhixuan, Yang Jun

2017, 31(6): 311-316. doi: 10.3969/j.issn.1007-2993.2017.06.010

[Abstract](43) [PDF 2150KB](7)

Abstract:
Unmanned Aerial Vehicle technology is becoming more and more mature. It has been used a lot in geotechnical engineering industry. However, the high price of UAV platform and professional software and the complexity of data processing have already limited the application of this technology. In this paper, the author used DJI phantom 4 drone and a software named Agisoft photoscan professional to explore a low cost technology which can sample the geographic information, build three dimensional model and complete data extraction. We hope to provide a reference for practical engineering applications.

Effect Analysis and Auxiliary Measures on the Construction Load around the Foundation Pit

Liu Jun

2017, 31(6): 317-320,323. doi: 10.3969/j.issn.1007-2993.2017.06.011

[Abstract](106) [PDF 621KB](13)

Abstract:
The reasonable value about the construction load around the foundation pit is related to the security and economy of supporting structure. The construction load contains the material loads and mechanical movement load. These two should not be repeated. When the construction load is 20 kPa, it can generally meet the temporary requirements on the construction load around the foundation pit, and at the same time, it also can let the construction vehicles walk. By the way, the load effect should be take special treatment when the construction vehicle is working.

Application of Underground Pipeline Detection Technique in Construction of Oil Pipeline

Cui Weiwei, Wu Xingbo, Ge Sheng

2017, 31(6): 321-323. doi: 10.3969/j.issn.1007-2993.2017.06.012

[Abstract](31) [PDF 678KB](6)

Abstract:
The main methods and means of underground pipeline detection are introduced. In the actual project, through the detection of underground pipeline detection and location technology status of underground pipelines, pipeline construction ensure the safety of the existing pipelines and the design rationality of the proposed pipelines. Greatly improve the safety and efficiency of oil pipeline construction.

2017 Vol. 31, No. 6