2010 Vol. 24, No. 3

Display Method:
Study on Dynamic Penetration Test (DPT) of Dynamic Consolidation of Foundation Soil
CAI Jianbo, LIU Lianggui, LI Youtian
2010, 24(3): 109-113. doi: 10.3969/j.issn.1007-2993.2010.03.001
Abstract:
The original terrain elevation difference is very large in a factory of Shenzhen. In order to flat ground, we use dynamic compaction (4 000 kN·m) to consolidation of foundation soil. Revealed by dynamic penetration test (DPT), there is the level of foundation soil stratification. Depth and DPT blow count is a function of cubic or power. Its the evidence of the dynamic consolidation of foundation soil by vibration waves (mainly P-wave) have been reinforced. There is no significant hierarchical feature, between the tamper-point foundation soils.
Study on the Transfer Mechanism and Settlement of Long Piles in Differnet Strata
QIU Rendong, SUN Yibin, SHI Yucheng
2010, 24(3): 114-118. doi: 10.3969/j.issn.1007-2993.2010.03.002
Abstract:
Based on the stastic tests' results of long piles in different strata, some conclusions about the load transfer mechanism and settlement of long piles under vertical loads are drawn. The settlement behavior of long piles in hard soil ground are simillar to the super-long piles in soft soil ground. The value of elastic compression of pile shaft are at a high proportion of the pile settlement, it should be considered in the settlement calculation. The ultimate capacity of end resistance and lateral resistance are not occurred in the same time under vertical loads. The ultimate capacity of lateral resistance are not occurred in the same time in different layers for a pile. We discussed the applicability of the ultimate bearing capacity formula of the Technical Code. At last,the authors point that the transfer mechanism and settlement of long piles' group foundation should be furher studied. And some important references for the theoretical research and technical application of super long piles are provided.
Analysis of Three-Dimensional Effects for Lateral Displacement of Non-supported Excavations
ZHANG Jianhui, ZHAO Jingli, WANG Daozhuo
2010, 24(3): 119-122,138. doi: 10.3969/j.issn.1007-2993.2010.03.003
Abstract:
For the three-dimensional effects caused by the excavation, the finite element software ANSYS is used to simulate the excavation process of a foundation pit with non-supporting structure. The distribution of the pit ground lateral displacement with every step of excavation was analyzed. The influence of the different angles of the pit on ground lateral displacement was studied. And, a distribution function of the pit ground lateral displacement was discussed. Some useful conclusions were obtained and the results may provide reference for the excavation design.
Study on Safety Assessment Index System for Subway Structure Based on Fuzzy Theory
LIN Nan
2010, 24(3): 123-125,160. doi: 10.3969/j.issn.1007-2993.2010.03.004
Abstract:
With the operation of the subway tunnel, more and more safety problems will appeare. Considering the selection principles of the evaluation index and the causes of safety problems existed in the shield tunnel structure, the paper determinates the evaluation index and establishes the safety assessment index system for subway structure which can be applied in Shanghai soft-soil areas and reflects the stress characteristics of the shield tunnel structure comprehensively. Applying the fuzzy comprehensive evaluation, the analytical hierarchy process and the pattern recognition theory, the paper then establishes the evaluation model of the subway structure and conducts the quantitative synthetic analysis and evaluation through a typical example, Very important significance will be made to evaluate the safety situation of the subway structure,modify the deviation and improve the overall safety level of subway system.
Disposal Measures and Instability Causation of the Slope Deformation of a Deep Foundation Pit Engineering
ZHANG Huaiwen, GAO Quanchen, YANG Wenli
2010, 24(3): 126-130. doi: 10.3969/j.issn.1007-2993.2010.03.005
Abstract:
With the dangerous situation of slope instability sliding and support deformation as well as the building subside increasing in the process of a deep foundation pit excavation, the multi-analysis and research ways which are composed of the field hydrogeology character surveying and support structure simulation with construction monitoring data analysis are used in this paper. The main causes which result in slope instability sliding are found the original silt and fine sand layer sedimentation which are strongly sensibility for construction disturbance. The treatment measures using the soil anchorage replaced of the concrete injecting are proposed and successfully applied on the field, which ensure for the deep foundation pit excavating safety and the slope final stabilization.
Primary Research on New Soil Stabilizer for Soft Subgrade
LIU Haibin
2010, 24(3): 131-134. doi: 10.3969/j.issn.1007-2993.2010.03.006
Abstract:
In last one hundred years, the research of new soil stabilizers has developed fast. Through analyzing the test results in laboratory and place of soil-cement or soil-stabilizer mixed pile sample, we discuss the feasibility of Soft Subgrade Soil Stabilizer in Shanghai. For the application of this new soil stabilizer, some suggestions are put forward too.
Study on Consolidation Calculation of Soft Ground Improved by DJM
HU Xuemei, LIU Jiacai
2010, 24(3): 135-138. doi: 10.3969/j.issn.1007-2993.2010.03.007
Abstract:
According to the practical foundation shapes, the consolidation models of the soil between piles and the substratum are built and solved respectively on the theory of Terzaghi-one dimension consolidation. Connected with the projects of highway, the research draws theoretical conclusions to compare with the in-site test results of DJM composite ground.
Research on Drying Shrinkage Experiment Method About Materials of Road Soil Subbase
CAI Xiaofei
2010, 24(3): 139-141,146. doi: 10.3969/j.issn.1007-2993.2010.03.008
Abstract:
Materials of road soil subbase need fine performance of drying shrinkage, this paper study on the size of specimen, designing of test mould and instrument, making and maintenance of specimen. Discussing the mechanism of drying shrinkage experiment, the method of testing and calculation, and the example of drying shrinkage experiment is enumerated, a drying shrinkage experiment method of soil is proposed.
An Experimental Study on Solidification/Stabilization of Organic Silt
FENG Cheng, WANG Baotian, LI Shoude
2010, 24(3): 142-146. doi: 10.3969/j.issn.1007-2993.2010.03.009
Abstract:
Solidification technology plays a very important role for reuse of dredging. The organic matter in the silt remarkably influences the effect of solidification. In order to assess this, an experimental program of organic solidification was undertaken, the mechanical impact of the organic matter on the solidification was evaluated, the result showed that sodium leads to the organic matter's dissolution, which would weakened the solidification effect of the soil,and the fly ash could undermines the hindering effect of organic matter on the cement hydration, it effectly enhanced the strength of the soil, at last, a new composite additive was proposed, when treated with this, the short-term and longt-terrn strength was greatly increased, the fly ash provided large amount calcium ion the late growth rate was continuously increasing with the increase of the fly ash.
Research on Secondary Consolidation of Structural Fuzhou Clays
WANG Juan, LUO Kaizhen
2010, 24(3): 147-150. doi: 10.3969/j.issn.1007-2993.2010.03.010
Abstract:
Based on a group of one-dimensional consolidation test of Fuzhou soft soil in undisturbed and remolded state the structural characteristics of soft soil is examined. Secondary consolidation properties of soft soil has been researched based on a series of one-dimensional secondary consolidation test for undisturbed samples and overload pre-pressure soft soil. The results show that the soft soil of Fuzhou is with structural, for that undisturbed soil and the remolded soil consolidation curve is obviously different; the separation of primary consolidation and secondary consolidation and the secondary consolidation ratio Cα of undisturbed soil are related to structural strength. These two characteristics are depends on preconsolidation pressure pp in structural damaged soil after preloaded.
Research and Analysis of Axial Force and Deformation in Retaining Structures of Deep Foundation Engineering
ZHANG Qinxi, HAN Yinshan, ZHANG Mingju
2010, 24(3): 151-155. doi: 10.3969/j.issn.1007-2993.2010.03.011
Abstract:
A large population and dense urban centers of the construction of the building subway, Subway Deep Foundation Pit engineering of deformation and the structure directly affects the safe use of surrounding buildings. Taking the practical project for example, monitoring the deformation and steel support axial forces of foundation pit structure. Through the practical engineering calculations, Gen-Slope numerical simulation data, design data and comparison of the actual test data, Discuss the various types of construction factors on the deformation of Retaining Structure and Construction of the significance Of information technology
Practice and Research of Groundwater Recharge in Shallow Confined Aquifer
WU Yongxia, ZHANG Nan, LU Jiansheng
2010, 24(3): 156-160. doi: 10.3969/j.issn.1007-2993.2010.03.012
Abstract:
The depth of confined aquifer in Shanghai is very deep. The waterproof curtain in deep foundation pit was hard to the bottom of confined aquifer, and the complete barrier to groundwater levels can't be done, then the environment must be impacted. According to the recharge experiment in the deep foundation pit of the shengda international financial center of Shanghai, the result that the artificial recharge has some effect for controlling the level of groundwater was achieved. In the end, according to the numerical simulation the change of groundwater level was gotten under different recharge conditions.
The Experiment of the Rmeability Law Under Temerature Function of Sandstone
GAO Hongmei, LAN Yongwei
2010, 24(3): 161-163. doi: 10.3969/j.issn.1007-2993.2010.03.013
Abstract:
Based on the previous experiments and fully taken account of changes in the internal structure of rock and changes of viscosity of water under the temperature the paper carries on experiments of permeability of sandstone selecting from fuxin under the high temperature. The experiment result is that the viscidity coefficient of drawing water reduces with the temperature rising, the permeability of the sandstone reduces with temperature increasing. Exploit the theoretical foundation in order to study formation geothermal development of Fuxin.