PSSLOPE

PSSLOPE Software and Soldier Pile Wall Design

The PSSLOPE software is a specialized tool used for soldier pile wall design. It integrates limited equilibrium stability analysis, the strain wedge model for soil/structure interaction, and a pile sizing routine. The program is LRFD compliant, internally factoring moment resistance by 0.9 and allowing users to factor the driving load manually.

Software Usage and Maintenance

The WVDOH permits the use of PSSLOPE by state and public users who have been properly trained for WVDOH projects. This software was developed under research project RP 213 by Dr. Mohamed Ashour. Users should note the following operational guidelines:

• Warranties: Neither the WVDOH nor the developer warrant the software to be free of defects; results must be verified by the user.
• Consistency Check: It is recommended to save work at regular intervals and restart the program before finalizing results to ensure consistency.
• Performance: The software is recognized for being relatively easy to use and providing accurate deflections consistent with more complex sizing methods.
• Documentation: The manual is accessible via the top menu within the program. The software can be Download the PSSLOPE Software.

Slip Plane Identification Modes

PSSLOPE offers three distinct modes for identifying the slip plane:

1. Defined Circular Slip: Allows the user to define a circular slip plane by entering three specific points.
2. Searched Circular Slip: The software searches for the weakest circular slip plane within user-defined ranges where the plane intersects the ground surface.
3. Simple Wedge Analysis: Suitable for routine shoulder failures. However, for slope failures located above the road, a defined slip surface analysis is required.

Design Criteria and Deflection Limits

The software allows for the input of geotechnical strength parameters. In cases where laboratory results are unavailable, the WVDOH Geotechnical Unit can provide conservative presumptive values.

• Factor of Safety (FS): A long-term FS of 1.3 is generally required, with a check for deflection in the service limit state (FS=1).
• Deflection Limits:
  • Adjacent to pavement: Limited to 1 inch.
  • At least 4 feet from pavement: Limited to 2 inches.

Pile Spacing and Lagging Specifications

Standard spacing for piles is 4 or 6 feet. Spacing greater than 6 feet is prohibited without a soil arching check to prevent ground loss beneath the lagging. When using 6-foot spacing, concrete must be placed to the bottom of the lagging.

Precast Concrete Lagging Requirements (6-foot spacing)

• Exposed Height up to 12 feet: 6-inch thick standard precast concrete lagging.
• Exposed Height 12 to 18 feet: 8-inch thick standard precast concrete lagging.

Abutment Pile Stabilization

PSSLOPE may be used to analyze the stabilizing effect of abutment piles for embankments 20 feet or less in height. For embankments exceeding 20 feet, the FS of 1.5 must be based on material strength and geometry alone, without considering the piles.

• Deflection: Free-head deflection is limited to 0.5 inches prior to bridge construction (service limit state).
• Flexure Check: The input FS must be increased so the overall initial and final FS reaches 1.5.
• Additional Analysis: A check for combined axial and flexure (e.g., in LPile) should be performed in the strength limit state based on the maximum moment resulting from the FS of 1.5.