Study On The Test And The Load-bearing Characteristics Of Half-screw Pile

Half-screw pile is a unique kind of variable section pile.It has many advantages,suchas good environment protection effect, wide applicability, reliable quality, high bearingcapacity of pile, The construction speed is fast, low comprehensive cost etc. However, useof half-screw pile is still at the initial stage for industrial and civil construction as well asfor roads and Bridges and some other areas. Study on half-screw pile’s bearing performanceis far behind it’s engineering practice.This paper introduces the calculation method of vertical bearing capacity underdifferent stress state, and a comparative analysis among three simplified calculationmethods was given based on the results of the static load test of single pile ultimate bearingcapacity of half-screw piles. A deep research of half-screw pile’s bearing performance wasdone based on the test of the pile body internal force of half-screw pile. The main researchand results were as follows:(1) The characteristics of half-screw pile/construction machinery/constructiontechnology and advantages compared with the ordinary piles were studied.⑵The rule of pile load, the load transfer characteristics and failure modes of threadsection of half-screw pile was analyzed. Summarized the existing method of determinesingle pile limit bearing capacity, and analyzed the influence factors of the half-screw pilebearing capacity.(3) Derivates formula of half-screw pile ultimate bearing capacity through existing pile-soil damage theoretical. And on the basis of static load test results, this paper analysis threekinds of simplified calculation method of single pile ultimate bearing capacity of half-screwpile. By comparing these methods, we know determining half-screw pile ultimate bearingcapacity should integrated variety of factors.⑷Using self-made stress and strain measurement device to measured the stress andstrain of test pile cross section. Combined with the static load test of half-screw pile thispaper do further analysis of the settlement of single pile/characteristics of pile shaft forceand pile side resistance, and provide a basis for the optimization design of half-screw pile.