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Liu P.,Huangpu Water Authority | Liu P.,Guangzhou Institute of Water Plan Investigation and Design | Liu P.,China Institute of Water Resources and Hydropower Research | Yang G.,China Institute of Water Resources and Hydropower Research | And 3 more authors.
Yanshilixue Yu Gongcheng Xuebao/Chinese Journal of Rock Mechanics and Engineering | Year: 2016

In order to study the influence of foundation scale on the bearing capability of rigid pile composite foundation, several groups of model tests such as the load tests under four different scale plates, foundation soil load test, composite foundation load tests and single pile load tests, were carried out using a model test apparatus made in-house. A series of test results were acquired. The results showed that with the same loading stress and pile replacement ratio, the composite foundation settlement and pile-soil stress distribution ratio increased with the increasing of loading plate scale. The load carried by the pile increased at the same time. Based on the test results, the scale effects of rigid pile composite foundation were analyzed from a theoretical point of view. The composite foundation load test did not perfectly represent the load bearing characters of the actual composite foundation because of the scaling effects. A new method to calculate the bearing capacity of the ground by overlapping the single pile and soil p-s curves were put forward to solving the problems of scale effects of composite foundation. Calculated results of model tests and engineering example showed that the method was feasible. © 2016, Science Press. All right reserved.


Zhang Y.-C.,China Institute of Water Resources and Hydropower Research | Yang G.-H.,China Institute of Water Resources and Hydropower Research | Yang G.-H.,Wuhan University | Hu H.-Y.,Pearl River Water Resources Scientific Research Institute | And 2 more authors.
Yantu Gongcheng Xuebao/Chinese Journal of Geotechnical Engineering | Year: 2012

Based on the construction of excavation cofferdams and pumping station foundation underneath pipelines in soft soils, the effect of the construction of excavation cofferdams and foundation on the pipelines and their protective measures are studied. The effect of the construction of the cofferdams and foundation on the pipelines is the key consideration because they are under the cofferdams and in the floor of the pumping station foundation. Therefore, based on the safety control standards, numerical models are establised to analyze the effect of the construction on them. The results show that the cofferdam construction has considerable vertical loading impact on the pipelines, inevitably creating the deformation of the upper soil and causing the displacement of pipelines in soils. At the same time, the stress state changes as well. However, using the appropriate reinforcement measures, the safety of the pipelines can be guaranteed during the construction. The present results can be used to optimize the design and construction and provide reference for other similar projects.


Yang F.,Wuhan University of Technology | Rui R.,Wuhan University of Technology | Liu P.,Guangzhou Institute of Water Plan Investigation and Design
Wuhan Ligong Daxue Xuebao/Journal of Wuhan University of Technology | Year: 2013

The newly-built structures may induce the safe problem of the surrounding pipelines and thereby the damaged pipelines may produce potential danger to the new buildings and surrounding environment. Therefore, the safety as-sessment of the pipelines has attracted much attention in the real application. The easy solution is to change the pipeline route but this approach may induce large expense and the delay of the construction procedure. Current approach for pipeline safety control is mainly based on monitoring. The abnormality of the collecting data demonstrate the damage or destruction and the normal performance of the pipelines cannot be ensured. A real large scale blowdown pipeline with steel thin wall is taken as the example to carry out the checking computation and safety evaluation based on corresponding codes and specifications. The theoretical computation and three dimensional numerical analysis is conducted for the structural checking. The performance of the pipelines are evaluated based on corresponding criteria and provided as the reference of the structural safety assessment.


Rui R.,Wuhan University of Technology | Yang F.,Wuhan University of Technology | Liu P.,Guangzhou Institute of Water Plan Investigation and Design
Yantu Lixue/Rock and Soil Mechanics | Year: 2014

There are a lot of kinds of underground pipes and structures in the urban area; the safety and regularly running of which must be taken into account during newly constructions. There are no generalized criterions to evaluate the safety and regularly running of them at present. It should be investigated which sectors the pipes belong to before construction, then their design and construction specifications can be used in the safety evaluation. Drainage design specifications are used to evaluate the safety of 2 large diameter steel sewage pipes with diameter of 1.2 m and thickness of 12 mm, during the cofferdam construction in the Litchi River in Guangzhou city. In view of the calculation methods in the design specification can not consider the interactions of all the effects during the construction. A three-dimensional simulation model of the whole cofferdam construction field stratum with the 2 large diameter steel sewage pipes is established. Deformation and stress of the pipes under 4 different construction conditions are calculated with FLAC3D. The equivalent stresses are calculated by fourth strength theory. The maximum value is 136.61 MPa, which appears at the outer surface of pipe No. 1 under the last construction condition. The maximum settlement of the pipe is 39.3 mm, which produces 0.275% declination of the pipe. The maximum stress value calculated by theoretical calculation formulas is 188.18 MPa, which is much higher than the result calculated by the current codes. The reason is that every effort is calculated independently and simply added in the theoretical methods. Finally, Deformation and strength of the pipes are checked according to relevant Chinese standards. It reveals that the sewage pipe lines are safe in the construction procedure and the results got by numerical simulation are more reasonable than those calculated by theoretical formulas.


Liu P.,Wuhan University | Liu P.,Guangzhou Institute of Water Plan Investigation and Design | Yang G.,Wuhan University | Yang G.,China Institute of Water Resources and Hydropower Research | Zhang Y.,China Institute of Water Resources and Hydropower Research
Advanced Materials Research | Year: 2011

The settlement of each part of the composite foundation, such as the foundation mat, cushion, soils and pile head, is recognized as equivalent under normal working conditions. On the basis of this, the corresponding load on long-short pile and soils can be derived easily from each individual p-s curve. The p-s curve of the composite foundation can be pictured in terms of the mutual actions of all the components mentioned above. and thus the corresponding settlement with load will be determined. Meanwhile, the p-s curve can be obtained via the undisturbed soil hyperbola tangent modulus method, which not only characters the nonlinear relationship between load and settlement very well, but also shows the deformation compatibility among those components. It is found that designed bearing capacity of soil is much higher than the reality based on usual design norms of composite foundation, while pile load is greater than the designed ones, which can be credited to the deformation compatibility of pile-soil not considered. © (2011) Trans Tech Publications.


Liu P.,Wuhan University | Liu P.,Guangzhou Institute of Water Plan Investigation and Design | Yang G.-H.,Wuhan University | Yang G.-H.,China Institute of Water Resources and Hydropower Research
Yantu Lixue/Rock and Soil Mechanics | Year: 2012

The nature of composite foundation is the load from the overlying shared by the reinforcement and ground soil via the deformation compatibility. Cushion plays a coordinating role of pile-soil deformation; however, its characteristics of the work and deformation characteristics are not yet clear. Designing cushion thickness still depends on experience or reference standard. It can not fully play the bearing capacity of foundation soil. The pile-soil deformation is usually adjusted by cushion in current composite foundation design. The pile-end piercing settlement coordinates pile-soil deformation and plays the role of foundation soil bearing capacity is ignored. Using pile-end piercing settlement to adjusted pile-soil deformation and bring foundation soil bearing capacity into full play, the cushion thickness is reduced or not to set cushion, and the designed pile length is shortened in order to reduce the cost of ground handling and achieve the purpose of load shared by pile and soil finally. A design method for pile-soil self-balanced composite foundation is established through controlling pile-soil deformations adjusted by pile piercing settlement. Through contrasting with the cushion method and project examples, it is proved that the method can show the foundation soil bearing capacity better, and provide references for the optimal design of composite foundation.


Liu P.,Hubei Engineering University | Liu P.,Guangzhou Institute of Water Plan Investigation and Design | Yang G.,Hubei Engineering University | Yang G.,China Institute of Water Resources and Hydropower Research
Yanshilixue Yu Gongcheng Xuebao/Chinese Journal of Rock Mechanics and Engineering | Year: 2011

According to design specification, soft soil rigid pile composite bearing capacity of soil between piles are often use too high, the settlement of soft soil under the corresponding designed load is greater than the settlement of composite foundation. But this situation can not happen in reality. So the bearing capacity of soft soil is not fully functional as designed load in engineering practice. The main reason is not considered the pile-soil deformation compatibility. In order to reveal the intrinsic relationship between the deformation compatibility and bearing capacity of soft soil being used much higher than the reality, the p-s curve of the pile and soil respectively is calculated by the tangent modulus method. Then, the rigid-pile composite foundation's p-s curve is determined by the p-s curves of the pile and soil. The relationship of the deformation compatibility of pile-soil will be established, on the basis of which the load-sharing case of the pile and soil can be analysed. It is found that the designed bearing capacity of soil is much higher than the reality based on normal design norms of composite foundation, while pile load is greater than the designed value. The bearing capacity or strength of pile is inadequate, which leads to foundation failure. For the lack of design norms methods, it was put forward that rational design of composite foundation should consider the deformation compatibility and bearing capacity of soft soil should be determined under corresponding the settlement in terms of its p-s curve. It is established the designed calculation of rigid-pile composite foundation in soft soil ground considering deformation compatibility of pile-soil. It provides a guide for design in the future.

Loading Guangzhou Institute of Water Plan Investigation and Design collaborators
Loading Guangzhou Institute of Water Plan Investigation and Design collaborators