China JingYe Engineering Corporation Ltd Company

Beijing, China

China JingYe Engineering Corporation Ltd Company

Beijing, China
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Fu W.,China Jingye Engineering Corporation Ltd Company | Yang Z.,China Jingye Engineering Corporation Ltd Company | Liu J.,University of Jinan | Zhuo Z.,China Jingye Engineering Corporation Ltd Company | Jiang X.,China Jingye Engineering Corporation Ltd Company
Yanshilixue Yu Gongcheng Xuebao/Chinese Journal of Rock Mechanics and Engineering | Year: 2012

Four selected engineering accident examples of composite soil nailing walls are particularly analyzed and studied;and some conclusions are drawn as follows. (1) When the safety factor of global stability checking of composite soil nailing wall meets the requirements of specification, the local stability can not be checked. (2) The "design bearing capacity" of nailing is difficult to be checked;and the"pull-out resistance of acceptance" could be adopted as the quality test standard and the basis of rod body strength design. (3) 6 kinds of composite soil nailing wall failure modes of the 13 kinds should be mainly checked and the other kinds could adopt structural measures, and so on. In addition, the research results include that:application conditions of composite soil nailing wall, methods of basic test and acceptance test of soil nailing, treatment principles of excavation of pit inside pit and edge-corner effect, exploration and survey requirements for surrounding environment, solution to bad engineering plan and coordination and lack of geotechnical engineering professional experience, etc. These theories research results have been reflected in the new implemented national standard of Technical Code for Composite Soil Nailing Wall in Retaining and Protection of Excavation.


Fu W.-G.,China Jingye Engineering Corporation Ltd Company
Yantu Lixue/Rock and Soil Mechanics | Year: 2015

The designing and calculating methods for compressive bearing capacity of a single pile can be divided into two types, i.e. characteristic value method and ultimate value method, in the Chinese codes related to pile foundations. The bearing capacity of a single pile is obtained by directly summarizing the skin friction and the tip resistance. These methods have some conceptual and theoretical disadvantages, since the skin friction and tip resistance cannot be simultaneously mobilized due to different mechanical responses and deformation requirements at the pile skin and the pile tip. The ultimate value method is more direct, reliable, accurate and clear in concept, and is more ready to be used in parallel to international standards. Hence it is suggested here that this method is preferred in the standards. A contradiction may occur in determining the uplift bearing capacity of a single pile according to the results of pull-out tests using the different standards. Because of this, the natural unit weight of pile should be used in calculation, instead of the buoyant unit weight of pile. Further research should be conducted to explore the following two phenomena in revising the relevant codes: one is that the unit skin friction decreases when exceeding the effective length of the pile, and the other is that tension coefficients for pull-out pile in some engineering is far less than the recommended values in the relevant codes, especially when pile length is longer. ©, 2015, Science Press. All right reserved.


Fu W.-G.,China JingYe Engineering Corporation Ltd Company
Yantu Gongcheng Xuebao/Chinese Journal of Geotechnical Engineering | Year: 2013

In the technical code, the bearing capacity characteristic value of composite foundation is the sum of bearing capacity characteristic values of piles and soils adjusted by empirical coefficients, which is called the characteristic value design method. Due to the difficulty of determing the empirical coefficients, it is not easy to obtain the accurate results. The bearing capacities of the piles and the soils are based on the load tests. In the load tests, the bearing capacity characteristic values of the composite foundation and soils are directly confirmed by the relative deformation value, but the bearing capacity characteristic value of pile is indirectly confirmed by the absolute deformation value that first determines the ultimate bearing capacity of single pile and then the characteristic value. The above methods and indexes are not matched, and it is a significant reason leading to the inaccurate calculated results by means of the characteristic value design method. In the limit state design method, when the piles reach the limit state, the soil state is regarded as the limit state. The ultimate bearing capacity of the composite foundation is the sum of the ultimate bearing capacity of the piles and the assumed ultimate bearing capacity of the soils, and the characteristic value takes half. This method needs less empirical coefficients, and it is practical, more correctness and safety when the conditions are enough.


Fu W.-G.,China JingYe Engineering Corporation Ltd Company
Yantu Gongcheng Xuebao/Chinese Journal of Geotechnical Engineering | Year: 2014

There are three test types of ground anchor such as basic test, creep test and acceptance test in China, and performance test, proof test and extended creep test in US, and investigation test, suitability test and acceptance test in EU. In addition, there are some tests for some determinate aspects of anchor performance in US and EU such as lift-off test, oscillating load test, testing of corrosion protection, test for cyclic work load, etc. The demands for anchor tests in US code is relatively simpler while more strict and precise in EU code. The meaning and function of basic tests on anchor attract no enough attention in China. It should be more zetetic but not proof for testing and understanding the anchor performances more adequately.


Fu W.-G.,China JingYe Engineering Corporation Ltd Company | Hu J.-L.,China JingYe Engineering Corporation Ltd Company | Zhang J.,China JingYe Engineering Corporation Ltd Company
Yantu Gongcheng Xuebao/Chinese Journal of Geotechnical Engineering | Year: 2012

There are some controversies on some rules for the prestressed anchors in some technical standards. There exist serious defects in soil anchor level rigidity coefficient formula, and meaning of the formulas is not clear, so we suggest to modify and improve it. In basic tests, the stable index 0.1 mm is a clerical error during the stability load period, it should be 1.0 mm; the anchor length should not be cut short since the shorter anchor gets the too high bonding strength; the maximum test load should be collapse load for the limit bond strength. The expanding detection numbers are suggested to 2 times the unqualified anchor numbers in acceptance tests. The timing method for the creep rate formula should be clear in the creep tests, otherwise the creep rate index would be meaningless. The free length of the anchor needs not be strictly limited, and it should be 4~6 m so as to better control the deformation of support system. The design service life of temporary anchors should be increased to 5 years from 2 years to better meet the needs of engineering now. The rule that the secondary grouting should be made after body strength achieves 5 MPa is hard to execute, so we suggest to make it during the period from the initial setting to the final setting.


Fu W.-G.,China Jingye Engineering Corporation Ltd Company
Yantu Gongcheng Xuebao/Chinese Journal of Geotechnical Engineering | Year: 2014

The overall processes of 5 unexpected dangers in foundation pits are introduced from their initiation to treatment. The discussions on the results of dealing with the dangers show that the current management system of emergency rescue is hard to make timely and accurate judgment and proper decisions, so the more efficient system named core technology expert system can be tried. Its running mechanism is as follows: (1) The key to the emergency rescue is to judge danger accurately, and the core technology experts are invited to undertake this role. (2) After the dangers happen, the emergency leading group and designers for foundation pit should judge the criticality first, and then the core technology experts further judge and report to the relevant government departments. (3) The project owner dominates the rescue work and the government mainly monitors the legitimacy of the procedure, and government power can be used when people really need to be evacuated. The proposed emergency management system can ensure the benefits of construction units, government and related dwellers.


Fu W.-G.,China JingYe Engineering Corporation Ltd Company | Yu H.-L.,China JingYe Engineering Corporation Ltd Company | Geng P.,China JingYe Engineering Corporation Ltd Company
Yantu Gongcheng Xuebao/Chinese Journal of Geotechnical Engineering | Year: 2010

Indicating value of dynamometer usually mismatches with that of lifting jack. Through the indoor and outdoor test and the analysis of engineering statistics, The reasons including errors of apparatuses, data, measure, frame member, assembling, and stress loss during stretching and locking of anchor, etc, are got. By applying dynamometer and jack together and founding the relation of indicating value, the stress of anchors could be analyzed more completely and accurately.


Fu W.-G.,China Jingye Engineering Corporation Ltd Company | Yang Z.-Y.,China Jingye Engineering Corporation Ltd Company
Yantu Gongcheng Xuebao/Chinese Journal of Geotechnical Engineering | Year: 2010

The development of supporting techniques can be divided into four stages: unconscious application, elementary application of multi-methods, soil-nail walls only and rational use of different methods. Now it is at the 4th stage. The excavation pits are large, deep, big, dense, near and complex. Among all the supporting techniques, the soil-nail walls occupy 50%, piles in row 40% and the others 10%. It is found that the diaphragm is not suitable for Shenzhen and the later braced piles method is more useful. The soil-nail walls and anchor bolts will be further limited because they are harmful to the surroundings and occupy the nearby underground space. Accordingly, the bracing system and the top-down construction has been widely used.


Fu W.-G.,China Jingye Engineering Corporation Ltd Company | Yang Z.-Y.,China Jingye Engineering Corporation Ltd Company
Yantu Gongcheng Xuebao/Chinese Journal of Geotechnical Engineering | Year: 2012

The prestressed anchors by pull-out resistance, cut-off curtains and mini-piles by shear strength together improve the overall stability of composite soil nailing walls. At present, it is the most mature and effective method for calculating the overall stability, which accumulates and reduces the resistance of these composite components. The key to the formulae is the reduction coefficient of breakdown resistance coefficient produced by the soil resistance, soil nails and composite components (the resistance coefficient is the ratio of the resisting torque produced by the components to the downturn torque produced by soil). They are empirical data and can be obtained from actual engineering data by inverse calculation arrangement according to certain assumptions. The studies on some critical excavations and the verified results show that there are reasonable ranges of combination coefficients when these components work individually and jointly, that is, they are 0.5~0.7 for prestressed anchors, 0.3~0.5 for cut off curtains and 0.1~0.3 for mini-piles. In addition, the sum of the breakdown resistance coefficients of soil and soil nails has the reasonable lower limit and it is about 0.86~0.97 (regardless of the other components function). When this condition is satisfied and the overall stability safety coefficient requirement is met, the movement of the excavations is generally small.


Fu W.-G.,China Jingye Engineering Corporation Ltd Company | Wu X.-J.,China Jingye Engineering Corporation Ltd Company | Zhuo Z.-F.,China Jingye Engineering Corporation Ltd Company
Yantu Gongcheng Xuebao/Chinese Journal of Geotechnical Engineering | Year: 2013

The complex relations between some nouns and terms about the bearing capacity of single pile, such as the ultimate standard value, standard value, characteristic value, design value, basic value and so on, are systematically summarized, and the concepts, naming and abolishing reasons of these nouns and terms in codes are clarified. The conclusions are as follows: (1) the nouns of the characteristic values of pile shaft resistance and pile tip resistance can be abandoned temporarily; (2) when the time is right, the nouns of basic value and design value of bearing capacity can be used again, the characteristic value of the bearing capacity can be modified to the design value of the bearing capacity, and the word the ultimate can be wiped from the noun of the ultimate standard value; (3) there are some theoretical disadvantages of formulas for calculating the bearing capacity of single pile in the foundation code and pile code, and the latter is relatively more direct and more reliable.

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