Discussion about the application of the anchor bar on the slope construction
Fu Ming Fu , Zhang Tian
Abstract: There are some advantages in strengthening slope with the anchor bar, such as low project cost, convenient for construction and so on. It not only meets the requirement of the reliability of the construction, but also is economic and reasonable for the construction.
Key words: anchor bar; slope; strengthening
1.Introduction
Anchor technique us strata geotechnical’s shear strength around bolt to deliver structures pulling force or keep strata of the excavation own stability. Due to the u of the anchor rod, Anchor strata produce compressive zone and have reinforcement effect to strata, can enhance the strength of strata, improve mechanical properties of strata, make structure and stratum together formed a kind of work together complex. Anchor system can effectively sustain tension and shear, improve shear strength of the potential sliding surface,
so it can effectively prevent slope to produce sliding damage.
Fig 1 after excavation of the slope
2.Project 骆驼简笔画profile
The length of a slope is about 60m, the most slope height is about 23m,the angle up to 50°~ 75°, a five-layer frame structure buildings is far from about 1.5 to 4m at its ba edge, its foundation is artificial bored pile and its bearing stratum is in weathered phyllite. Due to the strong weathering of rocks, it was chunky, looly structured, multi-muddy fillin
g. It has residual slope deposits of silty clay overlying and local folder with a pulpy, low strength. Slope had collapd at various locations, it is vary dangerous to the building, so we need to reinforce the slope, and we u stone concrete retaining wall and bolt to support it.
3.Bolt retaining and protecting design
3.1Bolt design
（1）all formation of anchor u whole length bond-type, the binder materials are ordinary cement mortar, the mortar strength grade is M30, the anchor length L is 10 meters, the slope height h is 9 meters. Anchoring ction length is 5m.
（2）According to the construction condition and the needs of the process, the layout form of anchor u quincunx, and in order to make the anchoring force in the role of surface rock surface with uniform, the two adjacent line bolts should be staggered arrangement.
（3）The anchor’s number according to h/3.24 per meter to calculation, the anchor length is L, a tolal of 252. The diameter of drilling holes is 90,the number of drill according to (L-0.1)m per hole to calculation, M30 grout number according to average 0.052m3 per hole to calculation.
（4）The two adjacent rows vertical spacing of anchor take 2.55m, horizontal spacing take 2.55m. The dip angle of anchor: with the angle of horizontal line is 20°, and drilling down with this Angle.
（5）Anchor u the steel bar, which is HRB400 level, 28mm diameter.
3.2Anchor calculation
（1）The calculation of lateral geotechnical pressure[1][2]
When the supporting structure to leave in rock and earth mass direction migration until to the limit equilibrium state, the geotechnical pressure which is role in supporting structure called active geotechnical pressure. Its calculation method is as follows:
For the slope which has no flare structure surface, generally speaking, failure is controled by rock mass strength, the calculation formula is same to the active soil pressure, but cohesive force C take zero, internal friction angle u (rock mass equivalent internal friction angle) instead of, according to the standard to lection; rupture angle is 45°+/2（is rock mass internal friction angle长征过草地, is estimationed by haircut at the standard 我不知道的英文of rock mass internal friction angle, reduction factor according to the standard to lection).
According to the engineering survey, active rock pressure can calculation as follows:
（2）the calculation of anchor tension design value
(1)
(2)
In the formula: is anchor tension design value; is a康熙皇帝的儿子nchor tension standard value; is partial load factor雪菊, take 1.3; is the horizontal tension standard value of anchor; is the 野生动物保护dip angle of anchor.
Through the calculation, =112.3kN =145.99kN
（3）the calculation of anchor steel 一本和二本的区别在哪里ction area政府工作
(3)
In the formula: is the steel ction area of anchor; is slope engineering importance coefficient(the slope engineering importance coefficient of this project is level 1, take 1.1); is the tensile working conditions coefficient of anchor bar ( permanent anchor take 0.69, temporary anchor take 0.92); is the tensile strength design value of anchor bar(standard value=400, design value=360).
