No full-text available
To read the full-text of this research,
you can request a copy directly from the authors.
Experimental research on implementing method of backfill of abutment back with horizontal flexible-reinforced grouting technology
Abstract
The construction technology, implement mechanism, reinforcement efficiency of implementing method of backfill of abutment back with horizontal flexible-reinforced grouting technology were studied by in-situ experimental research combining with laboratory study. The in-situ test results show that the backfill of abutment back reinforced by the new horizontal flexible reinforced grouting technology has enormous advantages including easy processed, effectiveness, development and utilization value. On the processing of the in-situ test many valuable construction parameters and experimental data were obtained; and a lot of material resource could be used for changing the design and construction parameters so as to perfect the construction technology of the new technology. At the same time, a new engineering solution for the prevention and treatment of bridgehead jump-driving was offered.
Dams are mainly located at the deep alluvium, where large amount of sand and gravel is adverse to prevention of seepage and maintenance of stability of the dams. Therefore it is necessary to reinforce the dams by grouting, and the primary task is to do research on the laws of diffusion and distribution of the slurry in the alluvial layer. The present study is based on the traditional theory of grouting and the laws of diffusion and distribution of the slurry, the slurry splitting mechanism, the characteristics of soil reinforcement are obtained. In addition, it is found by on-site grouting model tests that the slurry is generally filling and splitting along the interface between the earth and rock, and mainly splitting in the horizontal direction in grouting reinforcement process. To improve the reinforcement effect, the repeated injection should be adopted in grouting process. The study results will facilitate future dam grouting reinforcement projects in alluvial layer.
Settlement of roadway pavement surfaces near highway bridge abutments often leads to abrupt grade differences at the abutments. These grade differences subject vehicles to a bump, which may lead to driver discomfort and potentially unsafe driving conditions. Furthermore, differential movement requires costly and repeated maintenance work that usually impedes the flow of traffic. The sources of differential movement in Illinois can be divided into six major categories: (a) compression or erosion of materials at the approach embankment-abutment interface, (b) a broken approach slab, (c) compression of foundation soils, (d) compression or internal erosion of embankment soils, (e) poor construction grade control, and (f) areal distortion of foundation soils. An approach gradient equal to or greater than 1/100 to 1/125 appears to cause rider discomfort and therefore is proposed as a criterion for initiating remedial measures.
Interface bumps between bridge abutments and embankments increase risk and add over $100 million to maintenance expenses every year. New research reveals effective ways to deal with the bump problem. These include abutment and embankment on strong natural soil; long enough and strong enough approach slab; well compacted or stabilized fills; good fill material; good drainage; low embankments; adequate time period between fill placement and paving; good construction practice and inspection; and low track traffic.
Bolt and grouting reinforcement is an ideal measure for improving performance of bearing capacity of soft surrounding rock around tunnel in soft rock. Based on the test and research for fluidity, performance of separating water and compressive strength of fly ash and cement grouting material in laboratory, grouting material with a proper mixture rate is found (fly ash column fraction is less thorn 20%, water to cement ratio is from 0.65 to 0.70). An engineering practical example is given that fly ash and cement grouting has been used in very soft rock roadway at the Xinji NO.3 mine in Huainan.
The mass data in whole process of physical model test were real-time recorded; and the implementing mechanisms, reinforcement efficiency, construction technology of new horizontal flexible reinforced grouting technology were studied with physical model test in field. This paper focuses on the test design, manufacture scheme of model, testing method and research methods of experimental research. The test results show that the new horizontal flexible reinforced grouting technology contains enormous advantages including easy processing, effectiveness, and development and utilization value. It is indicated by the results of the experiment that the test results combining with the theoretical calculation have the guiding meaning for modifying the designing parameters. Meanwhile, the test results and construction parameters of the new technology can be used in real design and similar engineering for the test conditions of model test are basically in consistence with the conditions of actual operation.
The mechanical properties of lower activity fly-ash and effectiveness of its application to abutment-backfill are investigated by material experiment, centrifugal modeling test and numerical calculation. It is pointed that the properties of lower activity fly-ash are superior to that of other backfill materials. Its properties have the advantages of light mass, high strength and high modulus. In addition, its construction method is different from that of other materials. Its soil pressure and settlement are smaller than that of other materials markedly. Consequently, the results indicate that the lower activity fly-ash is recommendable backfill material.
Analysis of the harmful effect of vehicle bump at bridge-head of the highway and its mechanism
- Feng Z.-J
- Fang Y.-L
- Gong J.-C