International Journal of Earth Sciences and Engineering

Youping Wu ¹, Keneng Zhang ², Jie Liu ³, Jie He ³

Affiliations
1 Department of Geological Engineering, School of Geosciences and Info-Physics, Central South University, Changsha-410083, CN
2 Key Laboratory of Non-Ferrous Resources and Geological Hazard Detection, Changsha-410083, CN
3 School of Civil Engineering, Hunan University of Technology, Zhuzhou-412008, CN

Abstract

Flexible pile composite foundation can reduce the cost of foundation treatment, but its considerable settlement constrains its application. The solution proposed in this paper is a method of setting the pile with lateral constraint. Two comparative laboratory experiments were performed to analyse the lateral constraint pile’s influence on the composite foundation. The pile settlement and soil under the load were measured by monitoring the surface marks of the composite foundation. Soil and stresses in the composite foundation of piles were monitored through earth pressure cells placed on the foundation surface, the tips and bottoms of the piles and the PVC tubes, and the strain gauges on the pile shafts. The comparative experiments show that in the same experimental conditions, the settlement of the flexible pile composite foundation with lateral constraint is 25%-30% lower than that without lateral constraint, the stress on the pile tip is 18%-32% lower, and the stress in the pile shaft is also lower. These results indicate that the lateral constraint can effectively restrain the lateral deformation of the soft soil and improve the bearing capacity of the composite foundation.

Keywords

Lateral Constraint, Flexible Pile, Composite Foundation, Settlement, Stress.

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Da Hu ¹, Keneng Zhang ², Jie He ³

Affiliations
1 Key Laboratory of Metallogenic Prediction of Nonferrous Metals and Geological Environmental Monitoring, Ministry of Education, CN
2 School of Geosciences and Info-Physics, Central South University, Changsha, CN
3 Hunan University of Technology, Zhuzhou, CN

Abstract

Elastoplastic numerical calculation model for three dimensional finite element for tunnel is set up based on PLAXIS 3D and displacement prediction model for tunnel surrounding rock is established based on improved grey prediction theory; with stress distribution, strain pattern and displacement variation pattern in excavation process of tunnel analyzed, relation between parameter and deformation studied, calculation procedure and method for improved grey prediction theory presented so as to obtain settlement and displacement of arch crown in front of tunnel face within certain extent in tunnel excavation process by prediction. Suitong Tunnel is taken as test subject to carry out contrastive analysis relation among three displacement-time curves namely value of simulating calculation, predicted value and measured value and perform cross validation of the above mentioned three values. The validation result shows that the model is able to properly embody deformation pattern of surrounding rock, with prediction precision of displacement value satisfying requirement of specification and having larger scope of application in prediction of surrounding rock stability than that of other methods. The abstract section is mandatory, with a word limit of 200 words. The scope, aims, results and conclusions may be summarized here. Avoid inserting any reference in this section.

Keywords

Numerical Calculation, Grey Prediction Theory, Displacement Prediction, Tunnel Face.

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