Underground Coal Mining: Roof Support, Subsidence Control, and Strata Monitoring
Power Support in Longwall Mining
This section details different types of power support used in longwall mining and illustrates the structure and working of chock support with an example.
Types of Power Support Used in Longwall Mining:
- Chock Supports (Hydraulic Powered Roof Supports – HPRS): Most commonly used, these are heavy-duty, yieldable supports with multiple hydraulic legs.
- Shield Supports: Modern variants of chock supports with canopies and base units; they offer better coverage and control.
- Chock-
Urban Street Design: Principles, Paving, and Elements
Urban Street Design: Traffic Coexistence and Shared Spaces
Traffic Coexistence in Shared Streets: The movement of pedestrians, vehicles, bicycles, and buses often occurs on the same street, without strict differentiation between various modes of transport. In these shared streets, it is often challenging to allocate dedicated parking or pedestrian circulation space. Furthermore, bus movement can be difficult, and financial considerations are complex. These streets typically have a limited total
Read MoreCement and Concrete Essentials: Properties, Testing, and Application
Understanding Cement and Concrete Fundamentals
Key Properties of Cement
Initial and Final Setting Times
Initial Setting Time: It is the time interval between the moment water is added to the cement and the time at which the paste starts losing its plasticity.
Final Setting Time: It is the time taken from the moment water is added to the cement until the paste has completely lost its plasticity and has attained sufficient firmness to resist certain pressure.
Fineness of Cement
Fineness of cement refers
Read MoreUnderstanding Tire Types and Patterns
Tire Patterns and Classification
Block Pattern Features
- The block pattern offers improved braking performance and traction.
- The block pattern reduces skidding and hydroplaning on muddy or snow-covered roads.
- These tires tend to wear faster than rib or lug patterns.
- Resistance to wobble may decrease over time.
- The tread is susceptible to abnormal wear, especially on hard surfaces.
Important Tire Information
Unidirectional Tire Patterns
These are tires that have tread patterns with directionality relative
Read MoreHorizontal Curve and Road Design Problems
Problem 1: Circular Curve Design
A simple circular curve exists with a degree of curve D=12 and e=0.08. A structure is proposed on land on the inside of the curve. Assume the road is on level grade. Determine:
- The radius of the curve.
- The current maximum safe speed on the curve.
- The maximum distance allowable between the proposed structure and the centerline of the curve, such that the current maximum safe speed of the curve would not be reduced. Perception-reaction time is 2.5 seconds and fs=0.16
Solution:
Cargo Terminals: Types, Operations, and Handling Equipment
Cargo Terminal Types and Operations
General Cargo Terminals
Classification:
- Conventional: These are older terminals, initially not designed for unitized cargo. They feature a simple layout and generally don’t require extensive areas for cargo handling. Dimensions and installations depend on the cargo type, with open storage areas, light storage facilities, silos, and horizontal storage.
How They Operate
For loading and discharging, they use mobile shore cranes with a lifting capacity of 20-30 metric
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