Question 44 of 50

In the active case of a retaining wall, what is the term for the downward shear on the wall caused by the downward motion of the soil relative to it?

For a rough retaining wall with a granular backfill in the active case, what is the typical shape of the failure surface according to advanced studies?

What is the general equation of the logarithmic spiral commonly used in soil mechanics, where 'r' is the radius, 'r_o' is the starting radius, 'theta' is the angle, and 'phi'' is the angle of friction?

In the trial wedge method for evaluating passive resistance, what angle does the resultant force F1, acting along the logarithmic spiral surface BC1, make with the normal to the spiral?

Using the procedure of Terzaghi and Peck for a vertical retaining wall (theta = 0) with a soil friction angle phi' of 30 degrees and a wall friction angle delta' of 10 degrees, what is the approximate value of the passive earth-pressure coefficient, Kp, based on Figure 14.4?

Using the analysis by Shields and Tolunay for a vertical wall (theta = 0), what is the approximate value of the passive earth-pressure coefficient, Kp, for a soil with a friction angle phi' of 40 degrees and a wall friction to soil friction ratio (delta'/phi') of 0.6?

According to Zhu and Qian's method, what is the value of Kp(delta'=0) for a retaining wall with a vertical back (theta = 0 degrees) and a soil friction angle phi' of 30 degrees?

Using Zhu and Qian's method, what is the modification factor R for a retaining wall with a vertical back (theta = 0 degrees), a soil friction angle phi' of 35 degrees, and a wall friction ratio delta'/phi' of 0.8?

For a 3-m-high retaining wall with a vertical back (theta = 0) and horizontal granular backfill, given gamma = 15.7 kN/m^3, delta' = 15 degrees, and phi' = 30 degrees, what is the estimated passive force, Pp, using Shields and Tolunay's method where the coefficient Kp is found to be 4.13?

Why are Coulomb's and Rankine's theories generally not suitable for determining the earth-pressure distribution on a braced wall?

For a braced cut in granular soil (c'=0) with a soil friction angle phi' of 20 degrees, wall friction delta' of 10 degrees, and a resultant thrust application point represented by na = 0.4, what is the value of the non-dimensional active thrust Pa/(0.5*gamma*H^2)?

For a braced cut in a c'-phi' soil with phi' = 30 degrees, delta' = 10 degrees, na = 0.4, and a ratio c'/(gamma*H) of 0.1, what is the value of Pa/(0.5*gamma*H^2), assuming c'a = c'(tan delta'/tan phi')?

According to Peck's empirical pressure diagrams for the design of bracing systems in cuts in sand, what is the shape of the lateral pressure distribution envelope?

For a deep braced cut in sand with height H, soil unit weight gamma, and friction angle phi', what is the maximum lateral pressure, sigma_a, according to Peck's empirical pressure diagram?

For a braced cut in soft to medium clay, what is the expression for the maximum lateral pressure, sigma_a, when the stability number gamma*H/cu is greater than or equal to 4?

A 7-m-deep braced cut in sand has a calculated maximum lateral earth pressure (sigma_a) of 24.27 kN/m^2. The sheeting is analyzed as being hinged, and the calculated reaction at strut level C is 97.08 kN/m. If the struts are spaced at 2 m center-to-center, what is the design load for the strut at level C?

In the passive case, when a retaining wall is pushed into the soil, causing an upward motion of the soil relative to the wall, what is the resulting shear on the wall called?

What is a key geometric property of the logarithmic spiral r = r_o * e^(theta * tan(phi')) concerning the angle between any radial line from its center and the normal to the curve at their intersection point?

Using Zhu and Qian's method for a retaining wall with a vertical back (theta = 0 deg), soil friction angle phi' = 30 deg, and wall friction angle delta' = 15 deg (so delta'/phi'=0.5), what is the passive earth pressure coefficient, Kp? It is known that Kp(delta'=0) is 3.0 and the modification factor R is approximately 1.52.

In the analysis of passive earth pressure on a retaining wall under earthquake conditions by Subba Rao and Choudhury, at what inclination does the resultant passive force P_pe act?

For a braced wall with a granular soil backfill, at what approximate angle does the sliding surface typically intersect the ground surface?

For a braced cut in stiff clay, what is the suggested range for the maximum value of the apparent pressure envelope, sigma_a, according to Peck's empirical diagram?

A 7-m-deep braced cut has a calculated maximum lateral earth pressure of 24.27 kN/m^2. The sheeting is hinged at strut level B. The reaction forces are calculated as B1 = 18.2 kN/m and B2 = 0 kN/m. What is the total design load for the strut at level B if the struts are spaced at 2 m?

For practical considerations, what is the typical range for the angle of wall friction, delta', in the case of dense granular backfills, relative to the soil's angle of friction, phi'?

The assumption of a plane failure surface in Coulomb's theory is known to give reasonably good results for active earth pressure. However, for passive pressure, this assumption can be particularly problematic and lead to overestimation under what condition?

Using the procedure of Terzaghi and Peck for a vertical retaining wall (theta = 0) with a soil friction angle phi' of 40 degrees and a wall friction angle delta' of 20 degrees, what is the approximate value of the passive earth-pressure coefficient, Kp, based on Figure 14.4?

For a vertical wall (theta = 0) with a soil friction angle phi' of 35 degrees and a wall friction to soil friction ratio (delta'/phi') of 1.0, what is the approximate value of Kp based on Shields and Tolunay's analysis from Figure 14.5?

What is the value of Kp(delta'=0) for a retaining wall with an inclined back of theta = 15 degrees and a soil friction angle phi' of 25 degrees, according to Zhu and Qian's method (Table 14.1)?

What is the modification factor R for a retaining wall with an inclined back of theta = 10 degrees, a soil friction angle phi' of 45 degrees, and a wall friction ratio delta'/phi' of 1.0, according to Zhu and Qian's method (Table 14.2)?

For a soil with phi' = 30 degrees and a wall with delta'/phi' = 1, what is the approximate value of the passive earth-pressure coefficient K_pγ(e) under a horizontal earthquake acceleration of k_h = 0.2, assuming vertical acceleration k_v = 0?

Consider a soil with phi' = 20 degrees and a wall with delta'/phi' = 0.5. What is the approximate value of the passive earth-pressure coefficient K_pγ(e) under a horizontal earthquake acceleration of k_h = 0.3, assuming the vertical acceleration is equal to the horizontal (k_v = k_h)?

For a braced cut in granular soil (c'=0) with a soil friction angle phi' of 30 degrees, wall friction delta' of 15 degrees, and a resultant thrust application point represented by na = 0.6, what is the value of the non-dimensional active thrust Pa/(0.5*gamma*H^2)?

For a braced cut in a c'-phi' soil with phi' = 20 degrees, delta' = 0 degrees, na = 0.3, and a ratio c'/(gamma*H) of 0.1, what is the value of Pa/(0.5*gamma*H^2)?

In the determination of strut loads from empirical pressure diagrams, how are the vertical sheeting members assumed to be supported at the various strut levels for analysis?

When are passive pressure calculations that use a curved failure surface considered essential for design, as opposed to simpler methods assuming a plane-failure surface?

A 7-m-deep braced cut is made in sand with a unit weight of 16 kN/m^3 and a friction angle phi' of 30 degrees. Calculate the maximum lateral earth pressure, sigma_a, using Peck's empirical pressure diagram.

In the trial wedge method for determining passive pressure, how is the final, actual passive force Pp identified from the series of trial forces P1, P2, P3, etc., that are calculated?

Using Shields and Tolunay's analysis for a vertical wall (Figure 14.5), what is the approximate passive earth pressure coefficient Kp for a soil with phi'=25 degrees and a wall friction to soil friction ratio delta'/phi'=0?

A retaining wall has a vertical back (theta=0), and the backfill soil has a friction angle phi' of 40 degrees. What is the value of Kp when wall friction is zero (delta'=0), according to Table 14.1?

A retaining wall has an inclined back with theta=5 degrees, and the backfill soil has phi'=30 degrees. What is the modification factor R if the wall friction ratio delta'/phi' is 0.4, according to Table 14.2?

In the analysis of passive pressure on a retaining wall under earthquake conditions, where is the resultant passive force, P_pe, assumed to act on the wall?

For a braced cut in granular soil (c'=0) with a soil friction angle phi' of 45 degrees, wall friction delta' of 30 degrees, and a resultant thrust application point represented by na = 0.5, what is the value of the non-dimensional active thrust Pa/(0.5*gamma*H^2)?

A braced cut is in soft to medium clay where the stability number gamma*H/cu is less than 4. What does Peck's empirical diagram (Figure 14.11b) suggest about the apparent pressure envelope?

What is the formula for the area (A) of a logarithmic spiral sector from angle theta=0 to theta=theta1, given starting radius r_o, final radius r_1, and soil friction angle phi'?

From Terzaghi and Peck's wedge theory analysis (Figure 14.4), what is the approximate passive earth-pressure coefficient, Kp, for a vertical wall with phi' = 30 degrees and wall friction delta' = 30 degrees?

In general, how does the magnitude of the active thrust (Pa) on a braced cut, which rotates about its top, compare to the value of active thrust obtained by Coulomb's theory?

In the calculation of strut loads for the 7-m deep cut in Example 14.2, what is the calculated reaction A (in kN/m) at the top support (strut A)?

In Example 14.1, a 3m high wall has gamma=15.7 kN/m^3, delta'=15 deg, and phi'=30 deg. Several methods were used to calculate the passive force, Pp. Which method yielded the highest value?

The chapter on curved failure surfaces states that the assumption of plane failure surfaces, as in Coulomb's theory, can provide unsafe results in certain instances. Which two specific cases are mentioned as primary examples of this?