高等岩石力學102年第1學期期末考

臺北科技大學

高等岩石力學102年第1學期期末考

103.1.9

1.辨認岩石(10%)

2.a.何謂"size effect尺寸效應": 受力之物體或材料，其力學性質（例如強度、彈性模數等）受其尺寸之影響者，稱為尺寸效應。許多材料及物體之力學參數，常有隨尺寸之增大而下降之趨勢

b.E_t50 在強度50%下的切線斜率

          

 

 

 

 

 

 

c.Based on Elasticity,what is the relation 、 (10%)

側量壓力係數

波松比

3. A granitic rock is composed of a mixture of 30 % quartz, 40 % plagioclase, and 30 % augite. Its porosity is 3.0% and its longitudinal wave velocity measured in the laboratory is 3200 m/s. Describe its state of fissuring.(10%)

Solve:

quartz 30% 石英      V=6050m/s

plagioclase 40% 斜長石 V=6250m/s

augite 30%輝石       V=7200m/s

n=3%

由iq=49.7及n=3%查圖2.3，

約若在第III區，裂縫狀況：多裂紋(strongly fissured)

 

4.in a series of triaxial compression tests on a sandstone,the stress  and   at peak are follows.

Test	(MPa)	(MPa)
1	2.5	15
2	5	30
3	10	52
4	20	80

Determine values of Si and  that best fit the data

Sol:

 

 

 

Si=2.69MPa

5. A vertical hydraulic fracture was initiated in a borehole at a depth of 2500 ft. Assume the ground is saturated continuously from the surface and that the pressure in the ground water is hydrostatic. The water pressure was first raised 750 psi above the original groundwater pressure and then it was not possible to raise it further. When pumping stopped, the water pressure fell to a value 120 psi above the original groundwater pressure. After a day, the pressure was raised again, but it could not be pumped to a value higher than 100 psi above the previous pressure (the "shut-in" pressure). Estimate the horizontal stresses at the site of measurement, the tensile strength of the rock, and vertical pressure at the site. (10%)

Sol:

Unconsidered pore pressures ：

                                        

           

Consider  pore pressures ：

  

 

 

6.Assuming a reverse fault with its strike N50⁰E, the strength parameters of rock at a depth of 600 m before and after faulting are :qu=10MPa,  respectively. determine the orientation and magnitude of its maximum and minimum principle sresses before and after faulting, and estimate its dip at this fault.(density=27KN/m³)

Sol:

斷層前

(正斷層)

(逆斷層)

斷層後

(正斷層)

(逆斷層)

傾角約

 

7.with coupling of the normal deformation and shear deformation and dilatancy laws for rough joints,predict the path dependency doring a direct shaer test with no dilatancy

Sol:

 

 

8.explain rock mass classification(RMR & Q system) & their applicarion.

Sol:

RMR:Bieniawski南非評分法

1.      岩石材料強度 +15

2.      RQD         +20

3.      弱面間距     +20

4.      弱面狀況     +30

5.      地下水情況   +15

6.      弱面方位     -60

Q system:挪威BARTON岩體品質評分法

RQD 岩心品質指標

Jr:弱面粗糙度

Jw:弱面滲水情形

Jn:弱面組數

Ja:弱面品質

SRF:應力影響因素

由岩體分類可變形模數E、剪力模數G及求隧道荷重、開挖方法及支保設計

 

9.分析下圖主應力方向

 

 

 

10.stereographic projection as shown in Fig.5.6(b),explain the detail of the dispersed set 2 with a distribution of great circle girdle

 

 

 

 

 

 

 

Sol:

第一組散亂情形範圍大，第二組分散呈半月狀