What is the maximum slope considered safe for building construction?

The code advises against sites with a general slope steeper than 30 degrees. Such slopes are considered prone to instability and require extensive, costly stabilization measures (Clause 5.4.1).

What factor of safety (FoS) is needed for a cut slope?

A minimum FoS of 1.5 for permanent slopes under static conditions is the standard practice recommended. For seismic conditions, this can be reduced to around 1.1 to 1.2.

What is the difference between Part 1 and Part 2 of IS 14243?

Part 1 covers large-scale landslide hazard zonation (macro-zonation), while Part 2 provides guidelines for site-specific selection and development (micro-zonation).

Does this code specify how to perform slope stability analysis?

It doesn't specify formulas but recommends methods like the limit equilibrium method (e.g., Swedish circle method, Bishop's method) and advises considering factors like geology, hydrology, and seismic forces (Clause 7.1).

IS 14243

: 2000

Guidelines for selection and development of the site for building in hill areas, Part 1: Microzonation of urban centres

CurrentSpecializedGuidelinesBIMGeotechnical · Rock Mechanics

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This standard provides guidelines for urban microzonation in hill areas to assess natural hazards, primarily landslides and earthquakes. It outlines a methodology for creating hazard zonation maps by rating factors such as geology, slope, and seismic activity. The resulting maps help guide safe site selection and urban development to minimize risk to life and property.

Guidelines for selection and development of the site for building in hill areas, Part 1: Microzonation of urban centres

Quick Reference Values

Maximum recommended general site slope30 degrees (Clause 5.4.1)

Minimum factor of safety for permanent cut slopes (static)1.5

Minimum factor of safety for permanent cut slopes (seismic)1.1

Maximum height of unsupported vertical cut in hard rock6 m (Clause 7.2.1)

Minimum berm width on cut slopes1.0 m to 1.5 m (Clause 7.2.1)

Recommended slope for benches/berms1 in 10 towards the drain (Clause 7.2.1)

Key Formulas

F.S. = Σ Resisting Forces / Σ Driving Forces — Fundamental formula for Slope Stability Analysis

Practical Notes

Drainage is the single most critical factor for ensuring slope stability in hill areas; prioritize comprehensive surface and sub-surface drainage planning.

The guideline to avoid slopes steeper than 30 degrees is a crucial starting point. Developing on steeper slopes is technically possible but significantly increases complexity and cost.

This document is a 'guideline', not a mandatory 'code'. Its application requires significant engineering judgment and must be supplemented by detailed site-specific geotechnical investigations.