Xi'an, A High-rise Building Pile Foundation Engineering Quality Inspection Analysis

In the paper, pile' s quality testing is the object of researching. On the basis of collecting a lot of literature, some work were finished:1,I generalize some prevalent testing methods and their testing aim both in china and abroad now:a. bearing capacity test: static loading test and dynamical testing.b. pile' s quality test: the low strain test, the ultrasonic detecting method, port' s quality test and drilling core method.2, On the basis of a high-rise residential building' s pile testing in Xi' an, testing' s data were analysed.3, Through static loading test and finite element, etc to get their pile' s settlement and their ultimate bearing capacity, and analyse their difference.4, At last, some main conclusions are obtained. They are:a. the model of pile and earth act each other obtained by the three transmit function including in above resistance, side resistance and pile-earth have quite good referencement, according to which, the Q~s is quite good similitude. So we can forecast pile' s Q~s, bearing capacity.b. As for frictional piles, theory formula, finite element and high Strain are roughly identical to load-settlement curve provided by the site-static loading test, possessing quite good similitude. While the curve biven by the high strain test is significant different from the Practical survery effect, mainly showing the settlement is too big, the final settlement is 2.5 times the same as the static loading test.The reason is: in the process of the theory formule and finite element calculation, the parameters selected majority are average, while the real static curve is the comprehensive effect of the above pile and side pile in the dirrerent parameter model. The high strain survery makes dirrerence major in assuming the pile body material is ideal elastic, while in thework of the static load, the date of the pile body aixsi force labeled indicated that the force of pile body material and strain are not lineral. The second, the load exerced in high strain dynamic test is dynamic load, Under this load, side pile and end pile strength has some influence on the relation displacement, while the displacement of the pile end is the real displacement in the static test.c. As for frictional piles, in terms of code, finite element imitate, high strain surve test, and the single pile ultimate bearing capacity given by the static loading test are different, moreover the difference is significant. In term of the code, the bearing capacity given by the code is minimum, while the bearing capacity given by the high strain test is about 2 times the same as the design characteristic bearing capacity, the bearing capacity of the finite element imitate is maximum. It is consider from the scope of the static loading test, the bearing capacity given by the high strin and the finite element is quite good referencement. Analysis reason:the determination of the bearing capacity is influenced not only by the characterity of the foundation soil, but also by the foundation form, coad inclination and underground water level, so in terms of code determine the single ultimate bearing capacity is smaller that other three methods,while finite element, being choose the same model parameter, in the process of establish model, the parameters selected are average, and when the relative settlement is 40mm, the judge that the load correspond is ultimate bearing capacity has factor of person activity. The error of the high strain term of taking dynamic load, and the work Time of the load is too short, making the pile soil produces signigcant Accleration, and the soild body parameter can not gain by trail, and not Only be estimated by experience.The bearing capacity gained through the Static test is righter.