Chapter 12, Problem 12.7P

BuyFind*arrow_forward*

9th Edition

Braja M. Das + 1 other

ISBN: 9781305970939

Textbook Problem

Refer to Problem 12.6. In addition to the triaxial test, an unconfined compression test was conducted on an undisturbed sample of the same soil. If the compressive strength was found to be 95 kN/m^{2}, determine the pore water pressure at failure for the unconfined specimen.

**12.6** Consider the silty clay soil in Problem 12.4. If a consolidated drained triaxial test is conducted on the same soil with a chamber-confining pressure of 105 kN/m^{2}, what would be the deviator stress at failure?

**12.4** During a subsoil exploration program, undisturbed normally consolidated silty clay samples were collected in Shelby tubes from location *A* as shown in Figure 12.54.

**Figure 12.54**

Following are the results of four drained, direct shear tests conducted on the clay samples with each having a diameter of 63.5 mm and height of 32 mm.

To determine

Find the pore water pressure at failure for the unconfined specimen.

Explanation

**Given information:**

The diameter (*d*) of clay sample is

The height (*h*) of the clay sample is

The compressive strength

**Calculation:**

Calculate the area of specimen (*A*) as follows:

Substitute *d* in Equation (1).

Find the normal stress

Here, *N* is the normal force and *A* is the area of specimen.

Substitute *A* and *N* in Equation (2).

Similarly calculate the normal stress

Test no | Normal force, N(N) | Normal stress |

1 | 84 | 26.58 |

2 | 168 | 53.16 |

3 | 254 | 80.38 |

4 | 360 | 113.92 |

Find the shear strength

Here, *S* is shear force.

Substitute *A* in Equation (3).

Find the angle of friction

Here,

Substitute

Similarly calculate the angle of friction

Test no | Shear force, S (N) | Shear strength, | Angle of friction |

1 | 28.9 | 9.14 | 18.97 |

2 | 59.6 | 18.86 | 19.53 |

3 | 89.1 | 28.19 | 19.33 |

4 | 125.3 | 39.65 | 19.19 |

Find the drained angle of friction for the silty clay soil using the relation as follows:

Calculate the average value of angle of friction using Table 2.

Fundamentals of Geotechnical Engineering (MindTap Course List)

Engineering Fundamentals: An Introduction to Engineering (MindTap Course List)

Database Systems: Design, Implementation, & Management

Fundamentals of Information Systems

Mechanics of Materials (MindTap Course List)

Fundamentals of Information Systems

Principles of Information Security (MindTap Course List)

Automotive Technology: A Systems Approach (MindTap Course List)

A Guide to SQL

Principles of Information Systems (MindTap Course List)

Database Systems: Design, Implementation, & Management

Cornerstones of Financial Accounting

Precision Machining Technology (MindTap Course List)

Solid Waste Engineering

Electric Motor Control

Fundamentals of Chemical Engineering Thermodynamics (MindTap Course List)

EBK ELECTRICAL WIRING RESIDENTIAL

International Edition---engineering Mechanics: Statics, 4th Edition

Management Of Information Security

Systems Analysis and Design (Shelly Cashman Series) (MindTap Course List)

Steel Design (Activate Learning with these NEW titles from Engineering!)

Automotive Technology

Structural Analysis

Welding: Principles and Applications (MindTap Course List)

Enhanced Discovering Computers 2017 (Shelly Cashman Series) (MindTap Course List)

Network+ Guide to Networks (MindTap Course List)