Through analyzing causes of three kinds of quality accidents in construction of drill-grouting pile, which including short pile、broken pile and necking pile, and summarizes relative treatment, the result indicates which can meet demand of design and application.

In the process of optimal design of foundation reinforcement for the typical project,by means of finite element analytical method,systematic calculation and analysis have been conducted aiming at raft foundation and foundations reinforced by short pile,long pile,and long-short composite pile respectively.

It will reduce the construction cost and take less time to finish the project and use short piles and set supporting courses at shallower positions than usual according to the field condition.

Analytic method of pile displacement in long-short pile group subjected to vertical loading;

The stresses of long piles,short piles and soil were measured by the tests in situ on the bearing characteristics of cement-soil long-short piles composite foundation in deep soft soils;pile-soil stress ratio of composite foundation with cement-soil long-short piles and its variation rule with the load were studied in deep soils.

The mechanism between load and displacement of long-short pile foundation with end-bearing long-piles can be comprehended profoundly.

Experimental study of long-short piles composite foundation in deep soft soils;

Analysis of design project of long-short piles foundation of an engineering;

Cement mixing piles are put into the interval of pipe pile to form composite foundation long-short piles.

Application of foundation with long and short piles to chimney of a power plant;

Work mechanism of long and short piles composite foundation and its application

In view of the effective working lengths of pile bodies in ground treatment,an analysis is carried out on the work mechanism of long and short piles.