Study On Prestress Loss Of Prestressed Cable Anchor-pile Sheet Wall

Nowadays, the cable anchor reinforcement technology has been widely applied in the fields of mine , metallurgy , hydroelectric power, communication , civil construction, etc. The key of prestressed cable reinforcement technology lies in the size and loss degree of the prestress. Only if sustainable prestress is kept enough,the cable reinforcement can go its best. On the other side, the practice of the cable anchor reinforcement engineering on the slope and rock indicates that prestress loss is inevitable and objective . When the cable anchor is fixed,it has fixed loss. Affected by looseness of the cable,rock creep,rainfall,changes of temperature and groundwater and so on,the prestress of cable anchor also changes after the cable anchor is fixed. To sum up, the change of cable prestress is a focal issue in geotechnical engineering.Being one of the key problems in the cable reinforcement technology, the loss of cable reinforcement technology is related to the safety of cable reinforcement construction and durability. The proper measures of lowering prestress loss, of reducing prestress loss and of restraining the weakened or invalidity of cable reinforcement should be taken into serious consideration, which aims to preventing the large loss of engineering and safeguards people's life and property.With arranging the data of the prestress of certain freeway's PCAPSW in Chongqing and reffering some documents done by others,the thesis anasyses compeletly the CAP's fixed lossness of the prestressed cable anchor-pile sheet wall, influence of earth and rainfall to CAP and regularity of the fixed cable anchor's prestress. We find the main factors of the prestress losseness though theoretical calculation, and prestress loss by grey system theory non-equigap model. From the rearch and analses we can draw some conclutions as follow.(1)According to the field monitoring, the change of prestress of PCAPSW contains five courses: the first is the prestress in slow increase, the second step is that the prestess decreases and losses, the third course is prestress fluctuated reduces, the fourth is in sustainable decline and the fifth course is the prestress begins to level off.(2)By theoretical arithmetic,we make a conclusion that anchorage circle caused by anchorage retraction , losseness of cable and rock creep are main factors effecting the loss of prestress after cable locking.(3)By means of GM (1,1) model, we make tendency analysis of early changes of prestress of PCAPSW. The results explain that the model fitting is accurate and offer reference to the theory research and design of the prestressed cable anchor-pile sheet wall.(4)On the basis of sum-up of the prestress cable change rule and the factors effecting prestress, the measures of reducing the loss of prestress are put forward.